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Lecture 3: Key theories — Transcript

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  1. 0:05So I think we'll go ahead and start. I'd
  2. 0:08like to say good morning, good
  3. 0:09afternoon, good evening to you all and
  4. 0:12welcome to today's lecture in the course
  5. 0:14on key concepts in macro development.
  6. 0:17This course is organized as part of the
  7. 0:19STEG program. STEG is an acronym for
  8. 0:23structural transformation and economic
  9. 0:25growth. And the STEG program is a
  10. 0:27multi-year research initiative led by
  11. 0:29the Center for Economic Policy Research
  12. 0:31in London and funded and we're grateful
  13. 0:34for this by the United Kingdom's Foreign
  14. 0:37Commonwealth and Development Office as
  15. 0:39part of the UK aid effort. I'm Doug Gan.
  16. 0:43My colleague Joe Kabosi and I are the
  17. 0:45academic leads for the STEG program and
  18. 0:48along with a whole set of amazing
  19. 0:49colleagues at many universities around
  20. 0:51the world, we're excited to be offering
  21. 0:54this course.
  22. 0:56One of the explicit goals of the STEG
  23. 0:58program is to increase the number of
  24. 1:01researchers working on structural
  25. 1:02transformation of low and middle inome
  26. 1:05economies and to increase the quantity,
  27. 1:08quality and relevance of their research.
  28. 1:11That's where you all come in. The world
  29. 1:13needs a lot of smart, motivated,
  30. 1:16energetic people who can help us
  31. 1:18understand the really challenging
  32. 1:20questions that we face in relation to
  33. 1:22the the sources and patterns of economic
  34. 1:25growth and development.
  35. 1:27So with this course, we hope to share
  36. 1:29with all of you and and anyone else with
  37. 1:31an interest what we know and maybe more
  38. 1:35important, what we don't know about the
  39. 1:37topic. We're grateful that a lot of our
  40. 1:40colleagues have come together to
  41. 1:41contribute their time and their
  42. 1:43knowledge to putting together the course
  43. 1:45and we really appreciate their goodwill
  44. 1:47and generosity.
  45. 1:49I'm particularly delighted that today we
  46. 1:51have Berthold Herendorf a professor at
  47. 1:53Arizona State University to lecture on
  48. 1:56the topic key theories of structural
  49. 1:58transformation.
  50. 2:00Having started with some facts and
  51. 2:02descriptions of the patterns of
  52. 2:04structural transformation, Berthold is
  53. 2:06going to help us think about the broad
  54. 2:08classes of theories that might serve as
  55. 2:10frameworks for our thinking. So just a
  56. 2:13word or two about ground rules. Those of
  57. 2:16you who are in the virtual front row
  58. 2:18should please feel free to ask questions
  59. 2:20during the course of the lecture.
  60. 2:22Berthold has said he's happy to handle
  61. 2:25those questions. Others, please enter
  62. 2:28your questions in the Q&A section and um
  63. 2:32I and others will try to answer as many
  64. 2:34of those as possible. Please be aware
  65. 2:36that if you use the the hand button and
  66. 2:39try to put your hand up, the lecturer
  67. 2:41won't be able to see you. The lecture is
  68. 2:44being recorded and it'll be available on
  69. 2:46the STEG website and on YouTube for
  70. 2:48watching later. The presentation slides
  71. 2:51are available and I think the link is
  72. 2:54already in the chat window. So if you
  73. 2:56haven't already downloaded the slides
  74. 2:58and would like to have them to follow
  75. 3:00along, please um take a look in the chat
  76. 3:03window. And on that note and without any
  77. 3:05further ado, I'll turn things over to
  78. 3:07Burkeold. And thanks again.
  79. 3:11Yeah, thank you everybody.
  80. 3:13Let me share my
  81. 3:17screen. So you should be seeing the
  82. 3:20slides now, do you?
  83. 3:22Yes.
  84. 3:23Okay, that's good.
  85. 3:28Let me start with a few organizational
  86. 3:30details. I have chosen a teaching
  87. 3:31assistant.
  88. 3:33His name is Santiago Garcia Palto. He's
  89. 3:35a PhD student here at ASU. Was on the
  90. 3:38market and you will join Georgetown
  91. 3:41Qatar in the summer. So, if you want to
  92. 3:42go to the World Cup next year, there's
  93. 3:44your guy on the ground who already is
  94. 3:47talking about getting tickets for me.
  95. 3:49Anyway, more professionally, his email
  96. 3:52is Santiago Garcia at ASU.edu.
  97. 3:55Any questions you have, please contact
  98. 3:57him. There will be a tutorial session
  99. 4:00that Santiago holds on Monday, February
  100. 4:0422nd, that's the coming Monday, at 400
  101. 4:06p.m. UK time. I unfortunately will not
  102. 4:09be able to participate because that's
  103. 4:11exactly my teaching time for the
  104. 4:12undergraduates. But Santiago will be
  105. 4:14there. If you want him to answer any of
  106. 4:17your questions, just send him an email
  107. 4:19by 8:00 p.m. Sunday night UK time and he
  108. 4:22will organize those for the session.
  109. 4:25Otherwise, he will talk about a problem
  110. 4:27set which I've put at the end of the
  111. 4:29slides. The purpose of this problem set
  112. 4:32is to try and bring everybody up to
  113. 4:34speed because I will be the first person
  114. 4:37who probably talks about a dynamic
  115. 4:40channel equilibrium model. So far it was
  116. 4:42about facts and accounting. So the
  117. 4:45technical demand of this lecture is
  118. 4:47somewhat higher and I'm aware that we
  119. 4:50have a very heterogeneous group of
  120. 4:51people listening to the lecture. The
  121. 4:54purpose of the tutorial session is to
  122. 4:56help you catch up with what is in my
  123. 4:59lecture and give you some basic tools.
  124. 5:02The problem set is basically your way of
  125. 5:05practicing and then learning about the
  126. 5:08most basic version of the model that I'm
  127. 5:10going to discuss. Mine will be slightly
  128. 5:13more general, but that basic version has
  129. 5:17everything that you need to know if you
  130. 5:19want to solve a structural
  131. 5:20transformation model. Now Santi got that
  132. 5:23same type of lecture from me five years
  133. 5:25ago. So he should know how to do it.
  134. 5:27Probably he knows it better than I do
  135. 5:30and he will go through the derivations
  136. 5:32and answer questions in on Monday's in
  137. 5:34Monday's tutorial session.
  138. 5:39The background paper for today's lecture
  139. 5:41is a handbook chapter that I wrote
  140. 5:43together with Richard Rogers and Anakage
  141. 5:45Valentini. It's called growth and
  142. 5:47structural transformation and that's
  143. 5:49from the handbook of economic growth in
  144. 5:512014.
  145. 5:53So this was kind of a stupid little
  146. 5:55thing because Akosh and I got confused
  147. 5:58about the literature in 2008 and we
  148. 6:01wrote lecture notes. Lecture notes which
  149. 6:04basically were of the nature. We don't
  150. 6:06understand exactly what's going on.
  151. 6:07Everybody uses a different type of
  152. 6:09framework. There's so many different
  153. 6:11little effects. So what are the main
  154. 6:14forces behind structural transformation?
  155. 6:17And then luckily for everybody, Richard
  156. 6:19got asked to write a handbook chapter
  157. 6:21about structural transformation. And he
  158. 6:23asked me and said, "Do you have any idea
  159. 6:24what we should write or are you
  160. 6:26interested in participating?" And I
  161. 6:28said, "Yeah, I got these lecture notes
  162. 6:29here." And then Richard turned them into
  163. 6:32a very nice chapter with our help that I
  164. 6:36think has become a standard reference on
  165. 6:39growth and structural transformation. So
  166. 6:41I'm going to present core material from
  167. 6:43this handbook chapter. If you want more
  168. 6:46detail, please go to the printed
  169. 6:48version. In particular, I'm going to
  170. 6:51introduce the topic. Then I talk about
  171. 6:53some stylized facts, a background model,
  172. 6:57then what we perceive as a benchmark
  173. 6:59model of structural transformation, and
  174. 7:01then I'm going to conclude.
  175. 7:06Introduction. It's always good to define
  176. 7:08what you're talking about.
  177. 7:11Structural transformation is the
  178. 7:12reallocation of economic activity across
  179. 7:17broad sectors of the economy.
  180. 7:20Kusnits 50 60 years ago listed
  181. 7:23structural transformation as a key
  182. 7:25feature of modern economic growth.
  183. 7:30The typical split in sectors that people
  184. 7:33consider is agriculture,
  185. 7:36manufacturing and services.
  186. 7:40Agriculture and manufacturing are both
  187. 7:42producing goods. So they're tangible
  188. 7:46services produce intangible output. And
  189. 7:49then the difference between agriculture
  190. 7:51and manufacturing is that you presumably
  191. 7:53can eat agricultural output but not
  192. 7:55manufacturing output which uh is true
  193. 7:59for everything except for processed
  194. 8:00food. So that's very progressive. So the
  195. 8:03notion is you can't eat processed food
  196. 8:05or you shouldn't at least eat it. But
  197. 8:06anyway uh so this broad distinction in
  198. 8:10different sectors has proven very useful
  199. 8:14and it has turned out that structural
  200. 8:16transformation the reallocation between
  201. 8:18these three sectors has important
  202. 8:20aggregate implications
  203. 8:23when and if the sectoral composition
  204. 8:25matters. So for example,
  205. 8:28important implications have been found
  206. 8:30for labor market outcomes, productivity,
  207. 8:33the skill premium, urbanization etc.
  208. 8:38So the standard paper that is written on
  209. 8:42this in this theme is of the nature
  210. 8:46women don't do so well in agriculture
  211. 8:48but do way better in services. What are
  212. 8:51the implications of a dramatic
  213. 8:54transformation from agriculture into a
  214. 8:57service industry for the labor force
  215. 9:00participation of women or the wage
  216. 9:03premium, the wage gap between male and
  217. 9:07female salaries etc. This is a subject
  218. 9:10on which I think Rachel will
  219. 9:13pick up and and talk a lot about in the
  220. 9:15next lecture. So I'm just throwing this
  221. 9:18out here. The general way in which these
  222. 9:21papers are written is something differs
  223. 9:22across these sectors. Hence a change in
  224. 9:26the composition has aggregate
  225. 9:28implications.
  226. 9:33Now I'm going to focus on models with
  227. 9:35balanced growth and structural
  228. 9:37transformation.
  229. 9:39I will first present the stylized facts
  230. 9:42of structural transformation
  231. 9:44then develop a multis- sector extension
  232. 9:46of the one sector growth model that is
  233. 9:49consistent with these stylized facts and
  234. 9:51that serves as a natural benchmark model
  235. 9:54to start study structural
  236. 9:55transformation.
  237. 9:58Lastly, I asked whether it's possible to
  238. 10:00simultaneously deliver balance growth in
  239. 10:03structural transformation.
  240. 10:05Now that's actually harder than it
  241. 10:08sounds
  242. 10:09and I uh will report some success but
  243. 10:12also some models where this doesn't
  244. 10:15work. You might wonder why do we worry
  245. 10:18about balance grows at all. Uh the main
  246. 10:21reason is it's not only a feature that
  247. 10:24seems to come out of the data but it
  248. 10:27also implies that you can solve the
  249. 10:28models much more easily. It's like cop
  250. 10:31Douglas production functions. Balance
  251. 10:32grows in cop Douglas production
  252. 10:34functions. They're your friend. Whenever
  253. 10:35that's in the model, you're in business.
  254. 10:38Whenever it's not, well, you can still
  255. 10:40do it. But for an old guy like me, you
  256. 10:42have to simulate stuff. And I like
  257. 10:46balance growth because you can
  258. 10:48characterize the equilibrium
  259. 10:50analytically.
  260. 10:56Do interrupt me if you have questions or
  261. 10:58things don't make sense.
  262. 11:00Let's turn to the stylized facts of
  263. 11:02structure transformation. Before you
  264. 11:05talk about the facts, you always have to
  265. 11:08clarify how you measure the phenomenon
  266. 11:10you're after. So how to measure
  267. 11:11structural change or transformation?
  268. 11:16The three most common measures of
  269. 11:18sectoral economic activity are
  270. 11:21employment
  271. 11:23value added and final expenditure
  272. 11:26produced by a sector.
  273. 11:30Perhaps the most common one is
  274. 11:32employment shares because it's most
  275. 11:33commonly available and they are
  276. 11:36calculated either by using workers or
  277. 11:39hours worked if you have better data by
  278. 11:42a sector depending on what's there.
  279. 11:47Value added shares and final consumption
  280. 11:51expenditure shares are typically
  281. 11:52expressed in current prices. I call them
  282. 11:55nominal shares.
  283. 11:57The advantage of using current prices is
  284. 11:59that everything is the same unit and
  285. 12:01naturally shares make sense. If you use
  286. 12:05constant prices, everything is still in
  287. 12:07the same units. But often it's debatable
  288. 12:10what constant prices to use and how good
  289. 12:12they are. So if you have current prices,
  290. 12:16the most natural thing or perhaps the
  291. 12:19first thing to do is to calculate
  292. 12:21nominal shares.
  293. 12:23Now, if there are three measures, you
  294. 12:25wonder whether they all give the same
  295. 12:27answer. In a very broad brush sense,
  296. 12:30yes. But there are at least two reasons
  297. 12:33for differences among these three
  298. 12:35different measures.
  299. 12:37One is that investment and international
  300. 12:40trade
  301. 12:42imply that production and consumption
  302. 12:45don't necessarily coincide.
  303. 12:48and I can consume a lot of stuff that's
  304. 12:50produced in Europe like my car, the wine
  305. 12:53I drink, etc., etc. And so the
  306. 12:56consumption measure might differ from
  307. 12:59the production measure.
  308. 13:01The second reason why these measures
  309. 13:04might differ is that value added is a
  310. 13:07distinct concept from final expenditure.
  311. 13:10Now, usually I say that assume that
  312. 13:12everybody knows and then everybody knots
  313. 13:14and I move on. And over the years I
  314. 13:16found out nobody has the foggiest idea
  315. 13:17what I'm really talking about when I
  316. 13:19talk about value added and final
  317. 13:20expenditure. So I shouldn't say nobody
  318. 13:22but many people don't. So let's do one
  319. 13:25slide with some basic background
  320. 13:27concepts just to make sure we are all on
  321. 13:30the same page. Let's start really basic.
  322. 13:33What is an industry?
  323. 13:35It's a collection of establishments that
  324. 13:37produce similar goods or services. For
  325. 13:40example, the agricultural industry.
  326. 13:43They all produce edible tangible output.
  327. 13:49Now, establishments in these industries
  328. 13:52produce gross output
  329. 13:55by using the production factors,
  330. 13:57capital,
  331. 13:59labor, and intermediate goods.
  332. 14:05The establishments then sell the output
  333. 14:08either to final users for example
  334. 14:10households
  335. 14:12to other establishments or to
  336. 14:14themselves.
  337. 14:18What's a sector?
  338. 14:20Sectors sectors are aggregates of
  339. 14:23industries with similar characteristics.
  340. 14:25So the agricultural sector is all
  341. 14:28industries forestry, fishing,
  342. 14:32uh a livestock production etc. that are
  343. 14:37similar and can be summarized as
  344. 14:39agriculture.
  345. 14:42Now notice so far there's nothing that
  346. 14:45relates to value added. I've talked
  347. 14:47about final uses and I've talked about
  348. 14:49gross output which is final uses plus
  349. 14:52intermediate inputs for yourself and for
  350. 14:55others
  351. 14:56but I haven't talked about value added.
  352. 14:58So value added is somewhat of an
  353. 14:59artificial concept. If you really look
  354. 15:01at the data it doesn't immediately come
  355. 15:04out of the data. You have to take the
  356. 15:06value of gross output and subtract from
  357. 15:08it the value of intermediate inputs.
  358. 15:12Having said that, you should be aware
  359. 15:14that while it sounds obvious,
  360. 15:17it's often challenging in the data to
  361. 15:19find
  362. 15:21information on both and in particular to
  363. 15:24find constant prices for both if you're
  364. 15:27interested in real value added.
  365. 15:30Other than that, value added is the
  366. 15:32value added over the use of the
  367. 15:34intermediate inputs and uh you subtract
  368. 15:38get it by subtracting gross output. from
  369. 15:41gross output intermediate inputs.
  370. 15:45Distinct from that is final expenditure.
  371. 15:48It's not how much value you add but how
  372. 15:51much you actually deliver as a sector in
  373. 15:55terms of gross output to final users.
  374. 15:57This would be households or exports or
  375. 16:00anything that doesn't get further
  376. 16:03entered in the production process and
  377. 16:05modified.
  378. 16:08So final expenditure therefore are
  379. 16:10composite of the value added from
  380. 16:12different sectors
  381. 16:15and the uh composition of the final
  382. 16:19expenditure can be inferred from
  383. 16:22so-called total requirement matrix and
  384. 16:25we did that in a paper with the same
  385. 16:27co-authors in a in 2013. So if you're
  386. 16:30interested in the details go to that
  387. 16:31paper. I'm not going to have the time
  388. 16:34today to talk about that in this
  389. 16:36lecture.
  390. 16:39Instead, what I'm going to do is I'm
  391. 16:40going to focus on the production
  392. 16:42measures of structural change in
  393. 16:45particular employment shares and value
  394. 16:48added shares and give you some facts.
  395. 16:56Let's start with currently rich
  396. 16:58countries in particular Belgium, Spain,
  397. 17:02Finland, France, Japan, Korea,
  398. 17:04Netherlands, Sweden, the UK, and the
  399. 17:06United States. Why these countries?
  400. 17:09Because we found data for these
  401. 17:11countries reaching back till 1800.
  402. 17:15So what you see here is six plots,
  403. 17:19two for each of the three big sectors,
  404. 17:21agriculture, manufacturing and services.
  405. 17:25On the x-axis is always the share in the
  406. 17:28top three it's the employment share and
  407. 17:32the bottom three it's the value added
  408. 17:34share in current prices. So this is
  409. 17:36nominal shares.
  410. 17:39On the yaxis is the log of GDP per
  411. 17:42capita in 1990 international dollars.
  412. 17:46Richard talked about this. We want to
  413. 17:48use a unit that's the same in all
  414. 17:51countries so that we can compare GDP
  415. 17:54across countries and we want to take
  416. 17:56into account purchasing power par
  417. 17:59differences across countries. So
  418. 18:01international dollars do that.
  419. 18:05In the top three, as I said, it's the
  420. 18:08share of employment. And every dot is an
  421. 18:11observation from some year, which we
  422. 18:14don't care about. Important to us is
  423. 18:16that we have observations when these
  424. 18:18economies were rel relatively poor and
  425. 18:22observations when they were relatively
  426. 18:24rich. So each dot is an observation for
  427. 18:27a country and they're all put together.
  428. 18:30You can see a very clear pattern that is
  429. 18:34coming out of almost all documentations
  430. 18:38of the structural transformation facts.
  431. 18:40Namely, the employment share and
  432. 18:43agriculture is very large when you are
  433. 18:45poor
  434. 18:46and it falls to almost zero when you are
  435. 18:49rich.
  436. 18:51At the same time, the employment share
  437. 18:53of services is small when you are poor
  438. 18:57and it increases
  439. 18:59to around 80% when you are rich. So,
  440. 19:02agriculture is declining, services are
  441. 19:05increasing as GDP per capita increases.
  442. 19:10Manufacturing is somewhat of a weird
  443. 19:12sector because first it is increasing in
  444. 19:15employment shares but then there's a
  445. 19:18peak in the countries we have here Korea
  446. 19:23is included so the peak is fairly high
  447. 19:25at 04.5
  448. 19:28but afterwards the employment share of
  449. 19:31manufacturing falls.
  450. 19:35This is often referred to as a hump
  451. 19:37shape or an inverted U shape.
  452. 19:42If you go one, Was there a question?
  453. 19:46If you go one down, you see similar
  454. 19:49patterns for the value added shares. The
  455. 19:53agricultural shares fall, the
  456. 19:56manufacturing share follows a hump
  457. 19:57shape, and the services share increases.
  458. 20:02Now while they are similar there are
  459. 20:04some differences. One prominent one is
  460. 20:08that the value added shares of
  461. 20:10agriculture for poor countries tend to
  462. 20:13be considerably smaller than the
  463. 20:15employment shares.
  464. 20:17Which means that if you take value added
  465. 20:20per employed person the productivity of
  466. 20:24agriculture is low in poor countries.
  467. 20:27Now, Duck has important work on this,
  468. 20:29many other people, which wonders why so
  469. 20:33many people are in agriculture in poor
  470. 20:35countries, although they're really bad
  471. 20:37at producing it in terms of
  472. 20:39productivity.
  473. 20:42The second common feature is that the
  474. 20:44peak in manufacturing is around nine of
  475. 20:47lock GDP in 1990 international dollars.
  476. 20:52And that is also a GDP at which the
  477. 20:57value added share of services starts to
  478. 21:00increase. So you can think of this as
  479. 21:04not so much increasing and then an
  480. 21:06acceleration which happens here right
  481. 21:08around when the
  482. 21:11um peak of the manufacturing share
  483. 21:13happens.
  484. 21:15Lastly, it's important to recognize that
  485. 21:18even in very poor countries, there are
  486. 21:20market services
  487. 21:22and they seem to be reasonably
  488. 21:24productive at it, at least compared to
  489. 21:27agriculture, which I conclude from
  490. 21:29dividing this by this.
  491. 21:33Now, these are currently rich countries
  492. 21:36and a very long time series. If you want
  493. 21:38to convincingly document facts, it's
  494. 21:40always a good idea to not only look at
  495. 21:43the time series of a few rich countries,
  496. 21:45but also at the cross-section. And this
  497. 21:48is exactly what the next slide does. It
  498. 21:51uses the world development indicators
  499. 21:53because that has sectoral employment
  500. 21:55shares and the United Nations national
  501. 21:59accounts cross-sections between 1980 and
  502. 22:032000 in the upper case and 1975
  503. 22:07and 2005 in the lower case. Not going to
  504. 22:10go into the details.
  505. 22:13As you go away from currently rich
  506. 22:16countries who have even historically
  507. 22:18often fairly good data quality, stuff
  508. 22:21becomes a little more blurred and you
  509. 22:23get more outliers. But I think I can
  510. 22:26convince you with these two um panels
  511. 22:29here that similar patterns as before
  512. 22:32hold also in the cross-sections
  513. 22:35that is agriculture falls, manufacturing
  514. 22:38follows a hump shape and services
  515. 22:41increases.
  516. 22:44Now the noise around that is important
  517. 22:47if you look at a single country or group
  518. 22:50of countries but I would interpret this
  519. 22:52not as invalidating the facts but as
  520. 22:55being a deviation from the average which
  521. 22:58then might be worth exploring.
  522. 23:01So you might ask why is it that India
  523. 23:03has a large high-tech service sector
  524. 23:07which is not that usual for a country of
  525. 23:10its GDP per capita.
  526. 23:13But don't get confused and view
  527. 23:15everything as one data point that has
  528. 23:17nothing to do with anything else. I
  529. 23:19think it's good to have two things in
  530. 23:21mind. One thing is what are the stylized
  531. 23:25facts that hold very broadly across time
  532. 23:27and countries and what is the particular
  533. 23:30situation in the country that I'm
  534. 23:32studying and why would this be different
  535. 23:36from the broad facts in order to be able
  536. 23:39to do this one first has to understand
  537. 23:42what the forces behind the broad facts
  538. 23:44might be
  539. 23:47so summary when GDP per capita increases
  540. 23:52The shares of employment and nominal
  541. 23:54value added, nominal being incurrent
  542. 23:57prices,
  543. 23:58decrease in agriculture,
  544. 24:01increase in services
  545. 24:04and follow a hump shape in
  546. 24:05manufacturing.
  547. 24:08For low levels of development, meaning
  548. 24:12low GDP per capita,
  549. 24:15the value added share in agriculture is
  550. 24:17considerably lower than the employment
  551. 24:20share.
  552. 24:21that is agriculture is relatively
  553. 24:24unproductive.
  554. 24:28The employment share and the nominal
  555. 24:30value added share for the services
  556. 24:32sector are bounded away from zero even
  557. 24:36at very low levels of development.
  558. 24:40And for a log GDP per capita around 9,
  559. 24:44the increase in the nominal value added
  560. 24:47share in services accelerates
  561. 24:50and the nominal value added share for
  562. 24:52manufacturing peaks.
  563. 24:56Now the number nine is a little bit
  564. 24:58arbitrary you should be aware of because
  565. 25:01it depends on what prices I choose. This
  566. 25:03is in 1990 international dollars. If you
  567. 25:06move to more recent prices that might be
  568. 25:10underlying the current pen world table,
  569. 25:13the nine might change. The key thing is
  570. 25:16there is a middle income GDP, however
  571. 25:19you measure it, at which manufacturing
  572. 25:22peaks and services accelerate.
  573. 25:28So this is as much as I wanted to say
  574. 25:30about the stylized facts of structural
  575. 25:32change in the handbook chapter. I looked
  576. 25:35at it yesterday. Again, there's much
  577. 25:37more lengthy and detailed discussion. If
  578. 25:39you're interested, go there. It also
  579. 25:42includes measures of final expenditure.
  580. 25:45The basic broadbrush conclusions don't
  581. 25:48change. They the three key patterns
  582. 25:51namely decrease in agriculture, increase
  583. 25:53in services, some shape in
  584. 25:54manufacturing. And these are the three
  585. 25:58features that we would like a model to
  586. 26:00replicate.
  587. 26:11In order to be able to deliver such a
  588. 26:13model, it's useful to do a few
  589. 26:16background steps and look first at a two
  590. 26:20sector version of the growth model.
  591. 26:23Now, why two sectors? Well, the standard
  592. 26:26version of the gross model has one
  593. 26:28sector. If I talk about the reallocation
  594. 26:30across broad sectors, that's a
  595. 26:32non-starter.
  596. 26:33There's no reallocation in the standard
  597. 26:35gross model. That's why we use it often
  598. 26:37because it's so convenient. There's no
  599. 26:39role for relative prices to do anything
  600. 26:42interesting either because every
  601. 26:43relative price is one or constant.
  602. 26:49A two sector version is the first step
  603. 26:51of disagregating it. And this is going
  604. 26:55to be useful because it links what the
  605. 26:57structural transformation literature
  606. 26:58does to what the previous literature has
  607. 27:01done that focused on consumption and
  608. 27:03investment. I will briefly go through
  609. 27:06that and then I will disagregate
  610. 27:08consumption and look at structural
  611. 27:10change or structural transformation
  612. 27:12within consumption
  613. 27:14but keeping the structure of the two
  614. 27:17sector model the same. So this thing
  615. 27:19won't be thrown away. It's useful to go
  616. 27:21with me through that two sector model.
  617. 27:24It will just be the upper layer of a
  618. 27:26further disagregate structure into
  619. 27:28agriculture manufacturing and services.
  620. 27:31The model goes back to Ozava and I'll
  621. 27:33present a version building on Greenwood
  622. 27:35Heracowitz Cressel
  623. 27:40environment
  624. 27:42preferences and endowments. There is an
  625. 27:44infinitely life representative household
  626. 27:48who has preferences over consumption
  627. 27:50sequences
  628. 27:52that are described by the following
  629. 27:55separable utility function. The sum from
  630. 27:58time 0 to infinity
  631. 28:00of beta to the t
  632. 28:03time log of consumption.
  633. 28:06Beta is between 0 and one and is the
  634. 28:09discount factor. We need that to keep
  635. 28:11this infinite sum finite.
  636. 28:16Endowments. There's one unit of time in
  637. 28:18each period and there's a positive
  638. 28:20initial stock of capital K0 which is
  639. 28:24larger than zero. So to otherwise you
  640. 28:26won't get this economy off the ground.
  641. 28:32technology consumption C and investment
  642. 28:36X are produced from capital K and labor
  643. 28:40N.
  644. 28:42I'm going to follow the convention that
  645. 28:44uppercase let us refer to aggregate
  646. 28:47variables and lowerase variables to
  647. 28:50sectoral variables. So consumption and
  648. 28:53investment I'm going to call that
  649. 28:55aggregate and then capital is in each
  650. 28:57sector and labor in each sector.
  651. 29:01Production takes place in two separate
  652. 29:03sectors and the production functions are
  653. 29:05of the cog douglas form with the same
  654. 29:07exponents.
  655. 29:09So for example consumption is the
  656. 29:11capital in the consumption sector KC to
  657. 29:14the power theta
  658. 29:17time AC * N C which is technical
  659. 29:22progress in the consumption sector time
  660. 29:25labor to the power 1 minus DA.
  661. 29:30Technical progress here in the way it's
  662. 29:31written is labor augmenting. We probably
  663. 29:34all know that it doesn't matter for a
  664. 29:36cop Douglas production function because
  665. 29:38you could bring it up in front. But here
  666. 29:40it's written as augmenting labor.
  667. 29:44Changes in in a represent exogenous
  668. 29:48labor augmenting technical progress in
  669. 29:50that sector. And notice that the changes
  670. 29:53in A don't have to be the same and they
  671. 29:56will in general not be the same.
  672. 30:00What is the same here is the exponents
  673. 30:02theta on capital in the consumption and
  674. 30:07in the invest in the investment sector.
  675. 30:11Now at the beginning this usually takes
  676. 30:14some getting used to because most people
  677. 30:16say how plausible is that is that true
  678. 30:18in the data and the answer is no.
  679. 30:22But it turns out that
  680. 30:24first of all it's extremely convenient
  681. 30:26as I will show you in a minute and
  682. 30:29second you can still get the major
  683. 30:33developments of structural
  684. 30:35transformation
  685. 30:36if you assume this counterfactual equal
  686. 30:39exponents.
  687. 30:41So it's not true in the data but it's
  688. 30:43not of first order importance for what
  689. 30:44we want to do and it's convenient to
  690. 30:46assume these. So why is it convenient? I
  691. 30:50will uh come to that in a second by
  692. 30:53showing you the results for this two
  693. 30:54sector model. Let me describe the
  694. 30:56environment first.
  695. 31:01Capital accumulates as usual. You start
  696. 31:03with a capital stock KT, use it for
  697. 31:06production in period T. Then delta of it
  698. 31:10depreciates. So you're left with one
  699. 31:12minus delta KT. You add to that
  700. 31:14investment X and you get the capital
  701. 31:17stock in the next period. The
  702. 31:19depreciation rate is between zero and
  703. 31:21one
  704. 31:23as is usually the case.
  705. 31:27Capital and labor can be used in both
  706. 31:30sectors implying that feasibility
  707. 31:32requires that the total capital stock is
  708. 31:36at least as large as the sum of the two
  709. 31:38sectoral capital stocks and total labor
  710. 31:41which is normalized to one because
  711. 31:42there's a measure one of households
  712. 31:45is at least as large as the total labor
  713. 31:48in the two sectors NC and NX. X
  714. 31:56competitive equilibrium. I want to
  715. 31:59emphasize the role of relative prices
  716. 32:02and I therefore consider a sequence of
  717. 32:04markets competitive equilibrium as
  718. 32:06opposed to a planner problem. I could
  719. 32:08write down a planner problem where I
  720. 32:10only use preferences, technology, and
  721. 32:12feasibility. But that by construction
  722. 32:15would not contain any prices and there's
  723. 32:17important information in what the prices
  724. 32:20do. Therefore, I write down a
  725. 32:22competitive equilibrium.
  726. 32:25The investment good is going to be the
  727. 32:27numer that means its price is equal to
  728. 32:29one in each period.
  729. 32:31And I'm going to denote the price of
  730. 32:33consumption relative to the investment
  731. 32:35good by P.
  732. 32:38The rental prices for capital and labor
  733. 32:41are denoted by R and W. I'm following
  734. 32:44the notation that everything aggregate
  735. 32:48is uppercase letter. So that's why R and
  736. 32:50W are uppercase. I'm not sure it's
  737. 32:52ideal, but that's what we did in the
  738. 32:53handbook chapter. And one rule is if you
  739. 32:55did something in the past, don't change
  740. 32:57it because you get confused.
  741. 32:59Um, so R and W are rental prices for
  742. 33:03capital and labor.
  743. 33:06I assume that the household accumulates
  744. 33:07capital and rents it to the firm. So the
  745. 33:09household owns everything capital labor
  746. 33:12the firms here which is the most natural
  747. 33:14way of writing down the gross model
  748. 33:20characterization of equilibrium. Now if
  749. 33:23I was teaching at ASU I would go to the
  750. 33:26board and do a few derivations and
  751. 33:28explain the steps. Since I only have an
  752. 33:31hour and 15 minutes, I'm not going to be
  753. 33:34able to do that here. So, I'm just going
  754. 33:36to state main results in this model and
  755. 33:39I'm going to refer you to Santiago's
  756. 33:42tutorial session on Monday. So, he's
  757. 33:44going to through the steps and hopefully
  758. 33:46derive everything if you are interested.
  759. 33:49If you have seen these models, this is
  760. 33:51fairly standard, but it needs to be said
  761. 33:53nonetheless at least once.
  762. 33:56First the capital to labor ratios are
  763. 33:59equalized across the sectors at each
  764. 34:01point in time.
  765. 34:04So KCN C equal KXNX
  766. 34:07equal the aggregate KN and since labor
  767. 34:10is equal to one equal the aggregate
  768. 34:12capital stock. That's crucial because it
  769. 34:16means that you can do a lot of things in
  770. 34:19this economy that you couldn't otherwise
  771. 34:21do.
  772. 34:23This comes directly from the fact that I
  773. 34:25assumed that the exponents in the Cob
  774. 34:28Douglas production functions here are
  775. 34:31equal. If they're not equal, I would not
  776. 34:34get this result.
  777. 34:36with equal capital labor ratios. I can
  778. 34:40also show that the equilibrium value of
  779. 34:43the relative price
  780. 34:45of consumption to investment is pinned
  781. 34:47down by technology and equal to the
  782. 34:49inverse of the two labor augmenting
  783. 34:52technical changes.
  784. 34:54So if the
  785. 34:58excuse me if
  786. 35:01if the technical change term AX is very
  787. 35:05large
  788. 35:07relative to AC that means labor is very
  789. 35:11productive in investment production
  790. 35:13relative to consumption production then
  791. 35:16the price of investment is low relative
  792. 35:18to consumption or P which is the price
  793. 35:21of consumption to investment is high. So
  794. 35:24it's the inverse. The price of something
  795. 35:26is high if the a technical change term
  796. 35:30in the production of the item is low. So
  797. 35:35if you're very productive doing
  798. 35:36something, it's cheap. If you're not so
  799. 35:38productive, it's expensive relative to
  800. 35:40the other one.
  801. 35:42Second,
  802. 35:44equal capital to labor ratios mean that
  803. 35:47the model aggregates on the production
  804. 35:49side. By which I mean if you add
  805. 35:52investment and consumption in current in
  806. 35:55the same units
  807. 35:57namely investment which is the numerica
  808. 36:01then you get output Y in this economy
  809. 36:05and output Y is produced by an aggregate
  810. 36:08production function of the same form as
  811. 36:10the sectoral ones with the same theta
  812. 36:14but now plugged in aggregate capital K
  813. 36:18and aggregate labor one.
  814. 36:22So if you express everything in terms of
  815. 36:24investment, you need the investment
  816. 36:27augmenting technical change term. If you
  817. 36:30did it the other way around and
  818. 36:31expressed everything in units of
  819. 36:32consumption, you would have the
  820. 36:34consumption augmenting technical change
  821. 36:36here. Santi is going to talk more about
  822. 36:38that. I'm just going to state that and
  823. 36:39you have to take it at face value from
  824. 36:41me.
  825. 36:43So capital labor ratios are the same.
  826. 36:45prices are the inverse of the technical
  827. 36:47change terms and the production side
  828. 36:50aggregates.
  829. 36:55It is also true in this economy that the
  830. 36:58sectoral expenditure shares
  831. 37:01equal the sectoral employment shares.
  832. 37:06Now that's very convenient because it
  833. 37:08means that if I get the right behavior
  834. 37:11of the expenditure share then I'm also
  835. 37:14going to get the right behavior of the
  836. 37:16employment share. We have seen in the
  837. 37:17data that they behave similarly in the
  838. 37:20model they are the same. So we don't
  839. 37:21have to worry about that.
  840. 37:24Lastly, I get the standard oiler
  841. 37:26equation from the household problem
  842. 37:27which says consumption growth in terms
  843. 37:31of the numerator PCC or I should say
  844. 37:35consumption expenditure growth in terms
  845. 37:37of the numerator equals the discount
  846. 37:40factor plus 1 minus delta plus the
  847. 37:43rental price for capital.
  848. 37:47Again, Santi is going to derive all of
  849. 37:49this on Monday.
  850. 37:53We are interested in balanced growth and
  851. 37:55since this is a multis sector model I
  852. 37:57will focus on aggregate balance growth
  853. 37:59where balance growth refers to the
  854. 38:01aggregate variable but underneath there
  855. 38:03may be some changes.
  856. 38:06So I talk about an aggregate balance
  857. 38:08growth pass as an equilibrium pass along
  858. 38:11which the cult effects hold for
  859. 38:13aggregate variables that is constant
  860. 38:15growth of GDP per capita and capital per
  861. 38:18capita and constant capital GDP ratio
  862. 38:23real interest rate and capital income
  863. 38:25share and total income.
  864. 38:29Now for practical purposes and also to
  865. 38:32construct an aggregate balance gross
  866. 38:34path I'm going to assume that the
  867. 38:37sectoral TFP growth rates are constant.
  868. 38:41So ait + 1 / ait in each sector c or x
  869. 38:47is going to grow at a constant rate
  870. 38:49gamma i. Notice that these constant
  871. 38:53rates may well be different and in fact
  872. 38:56they should be different because we know
  873. 38:58that equipment in particular but
  874. 39:01investment more general has fallen in
  875. 39:03price relative to consumption. This
  876. 39:06would be captured here by having gamma
  877. 39:08for investment larger than gamma for
  878. 39:11consumption. Right? There's more growth
  879. 39:13in technical change in investment.
  880. 39:18The relative price does the opposite. it
  881. 39:20falls when the A's grow a lot.
  882. 39:26Now under these assumptions you can show
  883. 39:27that a unique aggregate balance gross
  884. 39:30pass exists in this two sector model.
  885. 39:36Sorry. Can I ask question?
  886. 39:38Of course you can.
  887. 39:39Yeah. So um we said earlier that the two
  888. 39:41sectors have different growth rate. So
  889. 39:43for instance the investment so the
  890. 39:45growth rate in investment sector is
  891. 39:47higher than the growth rate of
  892. 39:48consumption sector. Then why do we get
  893. 39:50the constant growth rate for the whole
  894. 39:52economy? Is it because of the bulos
  895. 39:54bulos disease we talked about before? Is
  896. 39:57it because because investment sector is
  897. 39:59higher uh tip growth then the pro and
  898. 40:03the relative price of investment will
  899. 40:05decrease so that the uh proportion of
  900. 40:08the investment sector in GDP has
  901. 40:10decreased is is it because of that or
  902. 40:13could you it's a good question. Uh let's
  903. 40:16go back to slide 16 at the bottom which
  904. 40:19defines GDP. It says GDP is X + P plus C
  905. 40:25time C. Now you point out correctly
  906. 40:29what's going to happen is there's
  907. 40:31stronger growth in X than in C. But GDP
  908. 40:35is not X plus C because I have to add it
  909. 40:37in the same units. GDP is X plus P * C.
  910. 40:42So the
  911. 40:44the weaker growth in consumption is
  912. 40:47going to get offset by the fact that the
  913. 40:49relative price of consumption is going
  914. 40:50to increase.
  915. 40:53Right? Look at the relative price. If
  916. 40:56consumption doesn't grow much but a
  917. 40:59investment grows a lot then this
  918. 41:00relative price grows a lot. And what's
  919. 41:03going to happen is that X and the
  920. 41:05expenditure on consumption, they grow at
  921. 41:08the same rate,
  922. 41:10but X and C don't. So the trick is the
  923. 41:14relative price that converts C into
  924. 41:17units of X is going to make sure that
  925. 41:19they're both on the same footing and
  926. 41:21grow at the same rate.
  927. 41:24Does that make sense?
  928. 41:25Yeah, thank you.
  929. 41:26So Santi is going to talk more about
  930. 41:28this. It is a good question and at the
  931. 41:30beginning when you haven't seen many
  932. 41:31multis sector models you get confused by
  933. 41:33this. Some people get still confused
  934. 41:36although they have seen a lot of those
  935. 41:38but the key thing is always make sure
  936. 41:40that everything is in the same units and
  937. 41:42you take into account both the real
  938. 41:45growth of the item you look at and the
  939. 41:48growth of its price.
  940. 41:52Let's put it differently. We are getting
  941. 41:54this massive increase of equipment. Why
  942. 41:57isn't that blowing up our GDP? Well, at
  943. 41:59the same time, the price of equipment is
  944. 42:01falling so much. So, my computer is
  945. 42:04always $1,500. Although the computer
  946. 42:06becomes better every four years
  947. 42:07dramatically, right? The computer
  948. 42:09becomes better, but the price falls. I
  949. 42:11always spend the same. So, that's the
  950. 42:13basic idea.
  951. 42:15Other questions?
  952. 42:18It's not the case. Let me then talk
  953. 42:21about structural change. So far, there's
  954. 42:22no structural change. there's just
  955. 42:25consumption and investment as and as
  956. 42:27Jean Lung has has pointed out they grow
  957. 42:30at the same rate if expressed in the
  958. 42:32same units.
  959. 42:35Now I'm going to now present a benchmark
  960. 42:38model of structural change which is
  961. 42:40going to disagregate consumption and
  962. 42:43focus on structural change within
  963. 42:45consumption.
  964. 42:46I will present three classes of
  965. 42:48preferences that give you structural
  966. 42:50change and then assess whether they're
  967. 42:52consistent with aggregate balance growth
  968. 42:54paths as defined before.
  969. 42:59Now I should say a couple of more
  970. 43:01sentences. This is a benchmark model
  971. 43:04that focuses on structural change within
  972. 43:06consumption
  973. 43:08which is a natural first step to take
  974. 43:10because consumption is roughly 80 85% of
  975. 43:14total GDP in most developed economies.
  976. 43:18It does leave the question open what
  977. 43:20happens to the rest and I'll get a
  978. 43:22little bit to that as we go through. But
  979. 43:24first let's talk about how you might
  980. 43:26generate structural change within
  981. 43:28consumption. The first class of
  982. 43:30preference is the generalized stiri
  983. 43:32preferences that Richard Akosh and I
  984. 43:34used in the AER paper that we had in
  985. 43:372013
  986. 43:39where you disagregate the sea from
  987. 43:41before
  988. 43:42into
  989. 43:44an aggregator
  990. 43:46that depends on consumption of
  991. 43:48agricultural goods, manufactured goods
  992. 43:51and services.
  993. 43:53In front there are weights omega a, m
  994. 43:57and s. And the exponents here, don't let
  995. 43:59them distract you. They're there so that
  996. 44:01the limits of these specifications
  997. 44:05are the right ones. More importantly,
  998. 44:09epsilon minus one over epsilon is the
  999. 44:12exponent on all three uh consumption
  1000. 44:15items. And then you take it the inverse.
  1001. 44:17So that's a CES production um utility
  1002. 44:21function with an elasticity of
  1003. 44:23substitution between the three that's
  1004. 44:26equal to epsilon.
  1005. 44:28Now it's not a CES in the strict sense
  1006. 44:31because there are additional terms here
  1007. 44:33C bar A and C bar S which are constant
  1008. 44:37terms both positive
  1009. 44:39and they imply that this utility
  1010. 44:42function is not homothetic.
  1011. 44:45What's a homothetic utility function is
  1012. 44:47one you can scale up and down. If you
  1013. 44:50double all expenditure, you double all
  1014. 44:53the um util all the consumption of each
  1015. 44:57of the different categories.
  1016. 44:59So if the bar terms here were zero, this
  1017. 45:02would be homothetic.
  1018. 45:06Non-zero bar terms introduce
  1019. 45:10non-homotheticities
  1020. 45:12which is a fancy way of saying you
  1021. 45:15consume more of some goods than others
  1022. 45:19and it changes as income changes. The
  1023. 45:22income elasticity in other words of
  1024. 45:24these different goods is not one.
  1025. 45:27This can be best illustrated if you look
  1026. 45:29at the implied demand system and I've
  1027. 45:31written it here at agriculture over
  1028. 45:33manufacturing expenditure services over
  1029. 45:36manufacturing expenditure first it's a
  1030. 45:40familiar term from CES utility functions
  1031. 45:44that just depends on the relative price
  1032. 45:48it's fixed ideas if epsilon is one then
  1033. 45:50I have log special case up there the
  1034. 45:54relative price doesn't matter the
  1035. 45:56expenditure shares are constant. If
  1036. 45:58epsilon is larger than one, you
  1037. 46:00substitute. What that means? If the
  1038. 46:02relative price of something goes up, the
  1039. 46:05expenditure share is going to go down.
  1040. 46:08And if epsilon is smaller one, the
  1041. 46:09opposite happens. You have compliments.
  1042. 46:11If the price goes up, the expenditure
  1043. 46:14share goes up because you don't
  1044. 46:15substitute as much as the price
  1045. 46:17increased or more. So that's the
  1046. 46:20standard CS here.
  1047. 46:24The nonometheticity
  1048. 46:26constants add additional terms here CA
  1049. 46:29bar and CS bar that are deviations from
  1050. 46:34the standard CS. In particular, in the
  1051. 46:37case of agriculture, there's a constant
  1052. 46:39term that you add. So if you
  1053. 46:42decide what to do in agriculture, you
  1054. 46:44first have to satisfy that constant term
  1055. 46:47and then the CES comes. The same is done
  1056. 46:50in services but you subtract that term.
  1057. 46:55Often the interpretation is this is
  1058. 46:57subsistence consumption. You have to eat
  1059. 46:59a minimum amount of calories otherwise
  1060. 47:01you die. Think of this as CA bar. The C
  1061. 47:05bar is often interpreted as home
  1062. 47:07production. Even if you don't purchase
  1063. 47:10any services in the market, you still
  1064. 47:12get some for free so to speak from a
  1065. 47:14market perspective. And these are the
  1066. 47:15ones which you produce yourself. So what
  1067. 47:18that means is that if you are poor, you
  1068. 47:20first satisi want to satisfy your
  1069. 47:22subsistence consumption of agriculture.
  1070. 47:26You are happy with your um home
  1071. 47:29production of services. So you subtract
  1072. 47:31something. So if you're poor, you will
  1073. 47:33spend relatively much on agriculture and
  1074. 47:36relatively less on services.
  1075. 47:39If you then increase your expenditure,
  1076. 47:43you will increase the expenditure on
  1077. 47:45manufactured goods and ultimately these
  1078. 47:48two terms will converge to zero and you
  1079. 47:50go to a CES. So this is a very simple
  1080. 47:52and cheap way of generating
  1081. 47:55nonomoticities
  1082. 47:57which imply that when you're poor your
  1083. 48:00composition is biased towards
  1084. 48:01agriculture and when you're rich it goes
  1085. 48:04more and more into services. You can
  1086. 48:06already see how structural
  1087. 48:07transformation is almost hardwired into
  1088. 48:09this specification.
  1089. 48:12Now I want to um for those of you who
  1090. 48:15have seen more in this literature make a
  1091. 48:17few remarks of two recent papers that uh
  1092. 48:21generalized this specification. So we
  1093. 48:23were perfectly happy with this
  1094. 48:24specification and then as always in life
  1095. 48:26somebody comes out and says it doesn't
  1096. 48:28always work and there's some
  1097. 48:29shortcomings and you get slightly pissed
  1098. 48:32off. I discussed this paper. I didn't
  1099. 48:34like it at the beginning. Now I like it.
  1100. 48:36So obviously progress means somebody
  1101. 48:38points out something better and one
  1102. 48:40better specification is kumin lashkari
  1103. 48:44mysteria that's in the fourth fifth or
  1104. 48:45sixth round I don't know of econometrica
  1105. 48:48I lost track.
  1106. 48:50They basically use what's called the
  1107. 48:52nonomothetic ces the same as before the
  1108. 48:55weights.
  1109. 48:57Then there is the consumption
  1110. 48:59agriculture manufacturing. Oh, sorry.
  1111. 49:02And services.
  1112. 49:04And now they introduce nonomaticities in
  1113. 49:07a different way. Not through constant
  1114. 49:09terms as we did and many people before
  1115. 49:12us. So I shouldn't claim here that's the
  1116. 49:15invention of this paper but we used it.
  1117. 49:18They introduced nonomaticities by
  1118. 49:20putting consumption with an exponent in
  1119. 49:23front of agriculture and services. So
  1120. 49:25intuitively what that does is as
  1121. 49:28consumption grows you can have different
  1122. 49:31weights depending on how much
  1123. 49:33consumption you have on agriculture and
  1124. 49:36services. So in particular if you want
  1125. 49:39that services get more and more of the
  1126. 49:43expenditure as you become richer you're
  1127. 49:46going to make the weight on this C here
  1128. 49:48large and you make it on this C small.
  1129. 49:52The implied demand system is the same as
  1130. 49:55before in the first part which is the
  1131. 49:58relative price effect. And then you can
  1132. 50:00see there is the consumption term that
  1133. 50:04is in front here and it depends on how
  1134. 50:07you choose the sigmas whether a good
  1135. 50:10becomes more or less important as
  1136. 50:12consumption grows.
  1137. 50:14And then there's another paper by Tim
  1138. 50:17Bapad that does something similar. He
  1139. 50:20uses piggle preferences.
  1140. 50:22I can never remember what piggle stands
  1141. 50:24for. It's price independent generalized
  1142. 50:26linearity which doesn't tell you much
  1143. 50:29but the demand function people use this.
  1144. 50:32I'm not going to go into the details of
  1145. 50:34this specification much. I just mention
  1146. 50:36it. It's an indirect utility function
  1147. 50:39which depends on expenditure and the
  1148. 50:41prices of goods and services. and he
  1149. 50:44again gets a demand system which depends
  1150. 50:46on relative prices and on expenditure.
  1151. 50:52So a similar a different way of getting
  1152. 50:56something similar the share of your
  1153. 50:58expenditure on goods here depends on
  1154. 51:01relative prices and it depends on how
  1155. 51:03much expenditure you have.
  1156. 51:06Now if you are interested in that
  1157. 51:07there's an excellent recent paper by
  1158. 51:09Teimo Bart himself and then Alder and
  1159. 51:12Müller in the AJ macro where they
  1160. 51:14generalize it to many goods. The
  1161. 51:16original paper just had goods and
  1162. 51:17services. I just flag this for those who
  1163. 51:21are particularly interested or somewhat
  1164. 51:22more advanced. If you didn't understand
  1165. 51:24the word I said when I discussed this
  1166. 51:26slide that's fine just ignore it for
  1167. 51:30now. We have three different
  1168. 51:32specifications and the key thing is as
  1169. 51:34already in the simplest specification
  1170. 51:37there's relative price effects and
  1171. 51:39there's effects of income that come
  1172. 51:42through nonomotheticity terms in the
  1173. 51:44simplest form the constants CA and CS.
  1174. 51:54So I need to also specify technology.
  1175. 51:57I'm going to stick to the cob daggers
  1176. 51:59production functions with equal shares.
  1177. 52:02But now I'm going to assume that there's
  1178. 52:05production functions for each
  1179. 52:07consumption category. Agriculture,
  1180. 52:09manufacturing and services separately.
  1181. 52:12Right? Before it was consumption,
  1182. 52:13investment. Now it's agriculture,
  1183. 52:16manufacturing, services and investment.
  1184. 52:19But the functional forms are the same.
  1185. 52:22And since the equal shares in the equal
  1186. 52:25exponents in the cob douglas worked so
  1187. 52:27well before I'm going to use them again
  1188. 52:31for those who want some further hints on
  1189. 52:34the literature there are three
  1190. 52:36generalizations of that in an important
  1191. 52:39paper in JPEG
  1192. 52:42generalized the
  1193. 52:45technology to allowing for different
  1194. 52:48exponents on the different production
  1195. 52:50functions.
  1196. 52:52And then we uh I mean we Akos and Chris
  1197. 52:56Harrington and I wrote a paper in the HA
  1198. 52:59macro where we estimated CES production
  1199. 53:02function and explored what that does to
  1200. 53:04structural change and a full-blown
  1201. 53:08model analysis of that is in Alvarez
  1202. 53:10Guard and Poshka which is in theoretical
  1203. 53:12economics in 2017. Again, this is not
  1204. 53:15meant as essential for this lecture, but
  1205. 53:18just as some suggestions for further
  1206. 53:20readings for those who are more
  1207. 53:22interested. So, you can generalize this,
  1208. 53:25but it's tedious. The most
  1209. 53:27straightforward thing is to work with
  1210. 53:28these
  1211. 53:32remarks. The literature often works with
  1212. 53:35only three production functions,
  1213. 53:38assuming that all investment is produced
  1214. 53:40in the manufacturing sector. Instead I
  1215. 53:44have here used four
  1216. 53:47distinguishing agriculture manufacturing
  1217. 53:49and services and that's just consumption
  1218. 53:51and then there's one investment sector
  1219. 53:53where nothing interesting happens in
  1220. 53:55structural change.
  1221. 53:57Why have I done that?
  1222. 54:00Assuming that all investment is produced
  1223. 54:02in the manufacturing sector is not
  1224. 54:04supported by the data. An easy way of
  1225. 54:06showing that is that
  1226. 54:09in the last 10 years, US investment
  1227. 54:11exceeded the value added the total value
  1228. 54:15added of US manufacturing.
  1229. 54:18So you can't possibly assume that all
  1230. 54:20investment is produced in manufacturing
  1231. 54:21because investment is more than
  1232. 54:23manufacturing value added. Why can that
  1233. 54:26be? Think of software.
  1234. 54:28Software is an investment. it's not
  1235. 54:30produced in the manufacturing sector and
  1236. 54:33it's becoming a bigger and bigger part.
  1237. 54:37I have therefore left investment
  1238. 54:39separate so that structural change
  1239. 54:41happens only within consumption.
  1240. 54:45Having said that view that is a natural
  1241. 54:47first step as always you got to start
  1242. 54:50somewhere and you better start somewhere
  1243. 54:52simple otherwise you don't understand
  1244. 54:53what you what you get. We since then
  1245. 54:57have continued working and in a recent
  1246. 54:59paper with Richard and Akosh which I
  1247. 55:02think is coming out in the review of
  1248. 55:03economic studies sometime this year we
  1249. 55:07characterize structural change within
  1250. 55:09investment as well and we focus as in
  1251. 55:12this paper on the aggregate balance
  1252. 55:14growth pass I should mention there's a
  1253. 55:17companion paper that was independent of
  1254. 55:19ours by Garcia Puan Masia Corta which
  1255. 55:22again takes gazillions of rounds in
  1256. 55:25econom Metrica and they do the same that
  1257. 55:29we did but they characterize investment
  1258. 55:31the structural change in investment
  1259. 55:33along transition path to the aggregate
  1260. 55:36balance growth pass. So our paper is
  1261. 55:37aggregate balance growth theirs is the
  1262. 55:39transition path which I admit is a lot
  1263. 55:42harder to do uh because you don't have
  1264. 55:44analytical solutions anymore. So if
  1265. 55:47you're interested in structure change
  1266. 55:48within investment there are two papers
  1267. 55:50that are currently at the frontier and
  1268. 55:53that talk about this. I should add it's
  1269. 55:56very messy. It took us forever to
  1270. 55:58understand how to characterize it along
  1271. 56:00the aggregate balance growth path. Uh
  1272. 56:03but it's done. I don't want to do it in
  1273. 56:06this lecture because I want to focus on
  1274. 56:08the essentials. So let's go back
  1275. 56:10structural change within consumption
  1276. 56:15and then there are some stupid
  1277. 56:16feasibility constraints as before. So in
  1278. 56:20this benchmark model I have
  1279. 56:24the same key properties from before
  1280. 56:27continue to hold.
  1281. 56:29In particular the capital to labor
  1282. 56:31ratios are going to be equal to the
  1283. 56:33aggregate capital labor ratio as before.
  1284. 56:37Why? Because I have fork of Douglas
  1285. 56:39instead of two but the exponents are all
  1286. 56:41the same.
  1287. 56:43Still the relative prices are determined
  1288. 56:45by technology. So relative price of two
  1289. 56:48things is the inverse of the technical
  1290. 56:51change terms.
  1291. 56:53Again the four sectors aggregate on the
  1292. 56:56production side. So I have an aggregate
  1293. 56:58production function of aggregate output.
  1294. 57:01And this was Jinglong's question. Why?
  1295. 57:04Because I'm taking the product for each
  1296. 57:07sector of price and output. And output
  1297. 57:09does whatever it does. But prices offset
  1298. 57:13this. So I can aggregate everything up.
  1299. 57:16the four sector model aggregates on the
  1300. 57:18production side and the sectoral
  1301. 57:20employment shares continue to equal the
  1302. 57:23sectoral expenditure shares which is
  1303. 57:24convenient. So I have just to look at
  1304. 57:26one and I know I characterize the other.
  1305. 57:32I can then analyze this more complicated
  1306. 57:35model with four sectors
  1307. 57:38by breaking the household problem into
  1308. 57:40two subpros. One is the intertemporal
  1309. 57:42problem from before. I allocate total
  1310. 57:45income
  1311. 57:46among the composite consumption good C
  1312. 57:49and savings which turn into investment
  1313. 57:53and then there's a static problem where
  1314. 57:56I allocate the period consumption
  1315. 57:58expenditure PC PTCT
  1316. 58:02among the three different consumption
  1317. 58:03goods agriculture manufacturing and
  1318. 58:05services
  1319. 58:08so going through the two sector model
  1320. 58:10before is useful to understand the
  1321. 58:13intertemporal problem.
  1322. 58:15What's new is the composition of
  1323. 58:18consumption follows from a static
  1324. 58:21problem. Now the structural
  1325. 58:24transformation that I'm trying to
  1326. 58:25generate and we'll show you in a second
  1327. 58:27how it results is going to happen within
  1328. 58:32consumption where the two sector
  1329. 58:34structure is totally unaffected but
  1330. 58:36within consumption there's reallocation
  1331. 58:38and the patterns that I showed you
  1332. 58:39before will happen.
  1333. 58:42Before
  1334. 58:46I show you the two key results, are
  1335. 58:48there any questions or things I should
  1336. 58:50clarify better
  1337. 58:52before I move on?
  1338. 58:55Excuse me. Uh yeah, I have a question
  1339. 58:58about the like total investment existing
  1340. 59:01uh the manufacturing. Uh how about if we
  1341. 59:04kind of uh add the durable consumptions
  1342. 59:07that treat like uh non-durable and uh
  1343. 59:10durable consumptions and uh separately a
  1344. 59:14separate sectors would would that help
  1345. 59:16like explaining and also taking out
  1346. 59:18inventories from investment uh
  1347. 59:21measurement how how much to what extent
  1348. 59:23would that help
  1349. 59:25um so it's a good question what you are
  1350. 59:29referring to if I understand correctly
  1351. 59:31is that in the national pounds.
  1352. 59:34The stock of durable consumption goods
  1353. 59:37like washing machines, furniture, etc.
  1354. 59:40is not capitalized. It's not part of the
  1355. 59:42capital stock. Okay? And the investment
  1356. 59:45in durables is expensed
  1357. 59:48not expensed is counted as consumption
  1358. 59:50expenditure but not as investment that
  1359. 59:53leads to a stock. If you reallocate the
  1360. 59:57investment in durables and add them to
  1361. 59:59the total investment that's otherwise
  1362. 1:00:02out in the economy, you make the problem
  1363. 1:00:05worse because you increase investment
  1364. 1:00:07even further. The manufacturing sector
  1365. 1:00:10is what it is already. Without durables,
  1366. 1:00:12the total investment exceeds
  1367. 1:00:15manufacturing value added. So if you add
  1368. 1:00:17some more, you make it worse.
  1369. 1:00:19Inventories won't help you. It's
  1370. 1:00:22actually very stark. What happens
  1371. 1:00:24basically is that about half of
  1372. 1:00:27investment is services
  1373. 1:00:30and you have to take that into account
  1374. 1:00:33if you want to match the composition of
  1375. 1:00:36investment seriously to the data. Now I
  1376. 1:00:38I already talked about software. Think
  1377. 1:00:40of other things. When you build a house,
  1378. 1:00:44there's design services, architectural
  1379. 1:00:48services, there's transportation
  1380. 1:00:49services, there's hotel and retail
  1381. 1:00:51services of all the materials that you
  1382. 1:00:54put in the house. So the house looks
  1383. 1:00:55like a physical thing and you say, well,
  1384. 1:00:57that was produced by the manufacturing
  1385. 1:00:59sector. In particular, where I live in
  1386. 1:01:01Phoenix, every house looks the same
  1387. 1:01:02standardized manufacturing sector. But
  1388. 1:01:05you overlook when you do that that
  1389. 1:01:06there's a huge service component in
  1390. 1:01:09these physical things because you for
  1391. 1:01:12starters have to get them from where
  1392. 1:01:13they were produced
  1393. 1:01:15to where you sell the house. I have a
  1394. 1:01:19stove for being pretentious from Italy.
  1395. 1:01:22So it was expensive to ship it over and
  1396. 1:01:24then there was a wholesaler here and
  1397. 1:01:26then there was a retailer here and then
  1398. 1:01:28it was put into my house. So there is
  1399. 1:01:30even in that physical house is a large
  1400. 1:01:33service component and what we argue in
  1401. 1:01:35the paper you have to take that into
  1402. 1:01:37account. It's it's an excellent question
  1403. 1:01:39but it's it's it's hard to weasel out
  1404. 1:01:42there
  1405. 1:01:43and it's so stark that if you really
  1406. 1:01:46want to do this you you should think
  1407. 1:01:48about structural change within
  1408. 1:01:49investing.
  1409. 1:01:51Other questions?
  1410. 1:01:52Thank you. That's very helpful.
  1411. 1:01:54May I ask a question sir?
  1412. 1:01:57Oh go ahead.
  1413. 1:01:58Yeah. uh I know this is a benchmark
  1414. 1:02:00model but uh I wonder that if we can
  1415. 1:02:04handle this issue within the
  1416. 1:02:06heterogeneous agent framework because
  1417. 1:02:08when I think about uh structural
  1418. 1:02:11transformation
  1419. 1:02:13uh what comes to my mind is that uh the
  1420. 1:02:16the switch of the labor market within
  1421. 1:02:18the ind different industries
  1422. 1:02:22so
  1423. 1:02:26to to fix ideas. So this is a
  1424. 1:02:29representative h agent model or
  1425. 1:02:32representative household model. So
  1426. 1:02:34there's no heterogeneity within the
  1427. 1:02:36households.
  1428. 1:02:38But what happens is that each household
  1429. 1:02:40is going to allocate its labor among
  1430. 1:02:43producing investment, agriculture,
  1431. 1:02:45manufacturing and services.
  1432. 1:02:47So within the household you can allocate
  1433. 1:02:51different shares of your total time
  1434. 1:02:53endowment of one two different sectors
  1435. 1:02:55and that can change over time.
  1436. 1:02:58Now another question that I sense from
  1437. 1:03:01your uh excellent question is what
  1438. 1:03:04happens if I have different households?
  1439. 1:03:07Maybe some are educated or not so
  1440. 1:03:09educated. Some are single, some are
  1441. 1:03:12married.
  1442. 1:03:13Some have a comparative advantage for
  1443. 1:03:16agriculture for some reason. Others have
  1444. 1:03:18a comparative advantage for services
  1445. 1:03:20perhaps of education.
  1446. 1:03:23You can extend this model and ask
  1447. 1:03:25questions in this context
  1448. 1:03:28because the production side is going to
  1449. 1:03:30be similar but now you have to work on
  1450. 1:03:31the
  1451. 1:03:33uh on the preference side on the
  1452. 1:03:35household side and make it more
  1453. 1:03:36complicated. Some people have started to
  1454. 1:03:38do this. I don't want to do it here
  1455. 1:03:41because I want to give you the benchmark
  1456. 1:03:43model and it's kind of hard. And it's
  1457. 1:03:45not hard, but it's I always find it
  1458. 1:03:47useful to think of the most simple
  1459. 1:03:49framework that has the essence of the
  1460. 1:03:51key effects. Once you understand that
  1461. 1:03:53you can complicate. If you start with a
  1462. 1:03:56complicated one, chances are you never
  1463. 1:03:58get the simple effects and that's why
  1464. 1:04:00I'm not I'm not doing that. Okay? But
  1465. 1:04:03it's a good question and um you can uh
  1466. 1:04:06check some people have worked on it. I
  1467. 1:04:08think Rachel is going to talk in the
  1468. 1:04:09next lecture about um such distinction
  1469. 1:04:14between men and women or skilled and
  1470. 1:04:16unskilled. I don't do it in in this
  1471. 1:04:19basic framework.
  1472. 1:04:24Well, if that's not the case, I have
  1473. 1:04:26about 10 minutes left. Let me come to
  1474. 1:04:29the key results then. Key results. The
  1475. 1:04:32first key result as I see it is from a
  1476. 1:04:34paper of Konamote rebell in the review
  1477. 1:04:37of economic studies and I'm going to
  1478. 1:04:38have labeled this income effects
  1479. 1:04:44take the utility function that we used
  1480. 1:04:47in our a paper
  1481. 1:04:51here it was
  1482. 1:04:54and impose that epsilon is equal to one.
  1483. 1:04:57If epsilon is equal to one, this utility
  1484. 1:04:59function reduces to a special case which
  1485. 1:05:02is called stone giri and that's lock
  1486. 1:05:05utility and here it is
  1487. 1:05:09where is it here.
  1488. 1:05:14So if epsilon is equal one the cs goes
  1489. 1:05:17away and I have a log utility in
  1490. 1:05:19agricultural consumption minus the
  1491. 1:05:21constant term manufacturer consumption
  1492. 1:05:24and services consumption.
  1493. 1:05:27On top of that assume that all sectors
  1494. 1:05:30counterfactually but just for the
  1495. 1:05:32purpose of this proposition have the
  1496. 1:05:35same growth rate of technical change. So
  1497. 1:05:37the gamma eyes are all the same.
  1498. 1:05:40If this is the case then there is an
  1499. 1:05:42aggregate balance growth path and along
  1500. 1:05:45the aggregate balance growth path
  1501. 1:05:47employment and expenditure shares are
  1502. 1:05:49constant for investment.
  1503. 1:05:51They decrease for agriculture.
  1504. 1:05:54they increase for services and they're
  1505. 1:05:56constant for manufacturing.
  1506. 1:06:00So under these stark assumptions
  1507. 1:06:04you get structural change out of
  1508. 1:06:06agriculture into services
  1509. 1:06:09but you don't get the hump shape in
  1510. 1:06:12manufacturing
  1511. 1:06:14at the same time you still get an
  1512. 1:06:16aggregate balance growth bus. So why is
  1513. 1:06:17that the case? Essentially everything is
  1514. 1:06:20growing at the same rate but these
  1515. 1:06:23constant terms CA and CS going to lead
  1516. 1:06:26to reallocation.
  1517. 1:06:28Think about it as follows. If CA is
  1518. 1:06:30close to C bar A,
  1519. 1:06:34this number is very small and the
  1520. 1:06:37curvature is very steep here. So you
  1521. 1:06:39want to allocate a lot to agriculture.
  1522. 1:06:42If you're poor and your consumption of
  1523. 1:06:45agriculture is close to C bar, you don't
  1524. 1:06:48worry much about services because you
  1525. 1:06:50get that constant turn for free. So even
  1526. 1:06:52if your service purchases were zero, you
  1527. 1:06:55would still not be at a corner. Now take
  1528. 1:06:58that economy and let it grow. The
  1529. 1:07:01relative importance of this bar term
  1530. 1:07:03here and this bar term there diminishes
  1531. 1:07:07as you grow and ultimately you go
  1532. 1:07:10towards a cog daggers function where
  1533. 1:07:13it's lock consumption of agriculture
  1534. 1:07:15manufacturing and services. So you go
  1535. 1:07:17through a composition omega a omega m
  1536. 1:07:21and omega s in the limit. Hence you go
  1537. 1:07:24out of agriculture towards omega A you
  1538. 1:07:26go into services towards omega s and you
  1539. 1:07:29get structural change but not in
  1540. 1:07:32manufacturing.
  1541. 1:07:35Second key result my emperor is relative
  1542. 1:07:38price effects.
  1543. 1:07:41Suppose that the growth rates of
  1544. 1:07:43technical progress are strongest in
  1545. 1:07:44agriculture second in manufacturing and
  1546. 1:07:47third in services.
  1547. 1:07:49Suppose that the nonomaticity terms C
  1548. 1:07:52bar A and C bar S are zero
  1549. 1:07:56and suppose that the elasticity of
  1550. 1:07:58substitution between these different
  1551. 1:08:01consumption goods is smaller than one.
  1552. 1:08:04There is an aggregate balance gross pass
  1553. 1:08:06again along which employment and
  1554. 1:08:09expenditure shares are constant for
  1555. 1:08:10investment. They decrease for
  1556. 1:08:13agriculture. the increase for services
  1557. 1:08:15and there lies somewhere in between the
  1558. 1:08:18other two shares for manufacturing.
  1559. 1:08:21So as before I get structural
  1560. 1:08:24transformation out of agriculture and
  1561. 1:08:26into services.
  1562. 1:08:28I don't get a constant share of
  1563. 1:08:30manufacturing necessarily anymore but
  1564. 1:08:31it's not clear that I get a hump shape
  1565. 1:08:33either.
  1566. 1:08:35So these were the two first models that
  1567. 1:08:38broke the ground and that highlighted
  1568. 1:08:42the two main effects namely income
  1569. 1:08:45effects in conjunction with non-homothic
  1570. 1:08:48utility functions that lead to
  1571. 1:08:49reallocation even if there's no price
  1572. 1:08:51changes. Notice here if all the gamas
  1573. 1:08:54are the same, the relative prices won't
  1574. 1:08:55change
  1575. 1:08:57or different gamas that lead to relative
  1576. 1:09:00price changes
  1577. 1:09:02but no income effects because the
  1578. 1:09:05utility function is homothetic. All the
  1579. 1:09:07bar terms are zero and then I get
  1580. 1:09:10reallocation
  1581. 1:09:11within consumption just from price
  1582. 1:09:14effects. In order to form intuition,
  1583. 1:09:17it's useful to go to the extreme case.
  1584. 1:09:19Think of a leontf.
  1585. 1:09:22If gamma a is the strongest in all
  1586. 1:09:26sectors, that means agriculture has the
  1587. 1:09:28strongest
  1588. 1:09:30techn technological progress, which
  1589. 1:09:32means that the relative price of
  1590. 1:09:34agriculture is falling. You're not
  1591. 1:09:36changing anything in your real
  1592. 1:09:38consumption bundle. The relative price
  1593. 1:09:40is falling. What happens with a share?
  1594. 1:09:41It's going down.
  1595. 1:09:45Similarly,
  1596. 1:09:46gamma s is the smallest. So the relative
  1597. 1:09:48price of services is increasing. You're
  1598. 1:09:51not changing your bundle in the Leontf
  1599. 1:09:53case which is the extreme form of
  1600. 1:09:55epsilon smaller than one. So services
  1601. 1:09:59become more and more expensive. The
  1602. 1:10:00share you spend on services is
  1603. 1:10:02increasing.
  1604. 1:10:03So that's a very mechanical and simple
  1605. 1:10:05way of getting you move out of
  1606. 1:10:08agriculture and you move into services.
  1607. 1:10:10The Hump shape is more challenging.
  1608. 1:10:16Additional results about the hump shape.
  1609. 1:10:19The paper by commenceri
  1610. 1:10:22shows that over very long periods our
  1611. 1:10:25utility function wasn't useful because
  1612. 1:10:27the income effects are persistent
  1613. 1:10:30and with our nonomothetic CES utility
  1614. 1:10:33function the income effects come for
  1615. 1:10:36constants. So basically what happens if
  1616. 1:10:38you go back to our uh demand system here
  1617. 1:10:45the nonomoticities come from constant
  1618. 1:10:47terms
  1619. 1:10:49and as PMC cm grows and grows and grows
  1620. 1:10:53these things converge to zero. So in the
  1621. 1:10:55limit they disappear. What they point
  1622. 1:10:57out is that income effects seem to be
  1623. 1:11:00persistent over long periods of time. So
  1624. 1:11:03their specification is more useful
  1625. 1:11:05because the income effect doesn't go
  1626. 1:11:06away. So you have that C here all the
  1627. 1:11:09time no matter how rich you are. And
  1628. 1:11:12then they do similar things as I just
  1629. 1:11:16discussed. They show that persistent and
  1630. 1:11:19income effects and the usual relative
  1631. 1:11:20price effects can replicate agricultural
  1632. 1:11:23and service shares over the long
  1633. 1:11:25horizon. But there's some challenge
  1634. 1:11:27still with the hump shape in
  1635. 1:11:29manufacturing. they no longer get an
  1636. 1:11:31aggregate balance gross path but an
  1637. 1:11:33asmtotic aggregate balance gross path.
  1638. 1:11:37And then a recent paper by Alder Müller
  1639. 1:11:40Bart uses the generalized pickle
  1640. 1:11:43preferences. It's going to be in print
  1641. 1:11:45in AJ macro I think this year. Again
  1642. 1:11:49they model persistent income effects
  1643. 1:11:51over long horizons and the usual price
  1644. 1:11:54effects and they get everything.
  1645. 1:11:57They replicate all shares including the
  1646. 1:11:59H shape in manufacturing over long
  1647. 1:12:01horizons and they have an aggregate
  1648. 1:12:03balance cross.
  1649. 1:12:06So in terms of achieving this what we
  1650. 1:12:10want namely aggregate balance growth and
  1651. 1:12:12the stylized facts stats as it stands
  1652. 1:12:14the gold standard
  1653. 1:12:16a little bit
  1654. 1:12:18um little bit unfortunate is that they
  1655. 1:12:21use an indirect utility function namely
  1656. 1:12:23this generalized piggle specification
  1657. 1:12:26which is not always the most intuitive
  1658. 1:12:28way of getting things. It's flexible, so
  1659. 1:12:31you can generate what you see in the
  1660. 1:12:33data, but it's a little bit hard
  1661. 1:12:35sometimes to keep track where the
  1662. 1:12:37effects come from. Still, I think if you
  1663. 1:12:39want the best model to replicate the
  1664. 1:12:42stylized facts, it's this one,
  1665. 1:12:47which leads me to conclude.
  1666. 1:12:51I've shown you that there are clear
  1667. 1:12:53stylized facts of structural
  1668. 1:12:54transformation.
  1669. 1:12:56Agriculture shrinks, manufacturing
  1670. 1:12:59follows a hump shape and services
  1671. 1:13:01expand.
  1672. 1:13:04I've illustrated in a benchmark model of
  1673. 1:13:07structural change two main forces.
  1674. 1:13:10One is relative prices change with a low
  1675. 1:13:13elasticity of substitution meaning the
  1676. 1:13:16different goods are complements in the
  1677. 1:13:19extreme case leontf
  1678. 1:13:21and so the sector with a low
  1679. 1:13:23productivity growth will expand
  1680. 1:13:26because you don't substitute much and
  1681. 1:13:28the share you spend on this will go up
  1682. 1:13:31and the sector with a high productivity
  1683. 1:13:33growth will contract. Why? again you
  1684. 1:13:36don't change the composition much and
  1685. 1:13:38the share you spend on it will decrease
  1686. 1:13:40in the model the expenditure and the
  1687. 1:13:44employment shares do the same thing so
  1688. 1:13:45once I have the expenditure shares I
  1689. 1:13:47know it's true also for employment
  1690. 1:13:48shares
  1691. 1:13:50the second effect that I've highlighted
  1692. 1:13:52is that income changes
  1693. 1:13:55can lead to structural change when there
  1694. 1:13:57are different income elasticities
  1695. 1:14:00luxury goods which are the ones that
  1696. 1:14:02have increasing shares and higher Income
  1697. 1:14:05elasticities expand when you develop. So
  1698. 1:14:09these are the services and necessities
  1699. 1:14:11as agricultural goods contract because
  1700. 1:14:14they have an income elasticity smaller
  1701. 1:14:16one. So the share goes down as you
  1702. 1:14:19develop.
  1703. 1:14:22The cess and the piggle utility generate
  1704. 1:14:25these forces and are consistent with
  1705. 1:14:27aggregate balance growth pass and the
  1706. 1:14:30nonomothetic sess which I forgot to
  1707. 1:14:32mention here can generate these forces
  1708. 1:14:34as well but is not consistent with
  1709. 1:14:38aggregate balance gross path instead it
  1710. 1:14:41asmtotically has aggregate balance grows
  1711. 1:14:44but along the transition it won't
  1712. 1:14:49now there's many different ways in which
  1713. 1:14:51you could generalize The results I've
  1714. 1:14:53shown you, I've hinted at some
  1715. 1:14:56developments which took place since we
  1716. 1:14:59published that handbook chapter in 2014,
  1717. 1:15:01which is already almost six, seven years
  1718. 1:15:03ago.
  1719. 1:15:05There's many more. We also have a
  1720. 1:15:07discussion in the handbook chapter about
  1721. 1:15:09future research and what we think might
  1722. 1:15:11be useful.
  1723. 1:15:13If you want a updated version, we have
  1724. 1:15:16uh Richard Akos and I published a paper
  1725. 1:15:19in uh the review of the Federal Reserve
  1726. 1:15:22of St. Louis. I believe it was in 2019
  1727. 1:15:27where we talk about some future de some
  1728. 1:15:30more current developments. So there's a
  1729. 1:15:32lot of work being done currently. I
  1730. 1:15:34think it's fair to say that the
  1731. 1:15:35benchmark model is still a useful
  1732. 1:15:38starting place, but lots of stuff and
  1733. 1:15:41exciting stuff has happened since and
  1734. 1:15:43Rachel in the follow-up lecture will
  1735. 1:15:45talk about some of it and the other you
  1736. 1:15:48will find in the journals. So that's all
  1737. 1:15:50I had to say. I think I did exactly an
  1738. 1:15:53hour 15 minutes given I started a little
  1739. 1:15:55late and I'm open for questions until
  1740. 1:15:5810:30.
  1741. 1:16:02Fantastic. Thank you so much, Berthold,
  1742. 1:16:04and thanks for being so prompt. Please,
  1743. 1:16:06um, those of you with cameras and mics,
  1744. 1:16:09please feel free to go ahead and pepper
  1745. 1:16:13Bertold with questions for the next 10
  1746. 1:16:14minutes.
  1747. 1:16:17Don't be shy,
  1748. 1:16:19guys. Another question.
  1749. 1:16:22Yeah, you know, but you only got two.
  1750. 1:16:23Okay.
  1751. 1:16:24Okay. What is the So, we saw that the
  1752. 1:16:28manufacturing is ham shipped. What is
  1753. 1:16:30your most preferred explanation for this
  1754. 1:16:32hamship? What is the intuition behind?
  1755. 1:16:38That's actually a good question and I'm
  1756. 1:16:39not sure I have an answer. So there's
  1757. 1:16:42there's different ways of of generating
  1758. 1:16:45it.
  1759. 1:16:47One the only one I covered in this
  1760. 1:16:50lecture was the alder, but there it
  1761. 1:16:52comes from
  1762. 1:16:54flexible income effects.
  1763. 1:16:57And so somewhat by construction, you can
  1764. 1:17:00get it if you free up your preferences
  1765. 1:17:04and you have strong and then weaker
  1766. 1:17:06income effects. So imagine if you're
  1767. 1:17:08relatively poor, you want a lot of
  1768. 1:17:10manufacturing goods no matter what they
  1769. 1:17:12cost. If you get richer, you want less
  1770. 1:17:14and less manufacturing goods. So that
  1771. 1:17:16that's one way. Another way is to um
  1772. 1:17:22free up the constraint that
  1773. 1:17:25technological progress grows at constant
  1774. 1:17:27rates.
  1775. 1:17:29Okay. So it it I don't know the exact uh
  1776. 1:17:34facts out of the top of my head but I'm
  1777. 1:17:36under the impression that that's a good
  1778. 1:17:38a reasonable assumption say for the
  1779. 1:17:41postwar US but not a reasonable
  1780. 1:17:42assumption over 200 years.
  1781. 1:17:45Okay. But I think it's I just refereed
  1782. 1:17:48on the weekend the paper that was
  1783. 1:17:50exactly about the hump shape and I think
  1784. 1:17:53uh there is a lot of interesting work
  1785. 1:17:55but it's not ultimately settled where it
  1786. 1:17:58comes from. I've always in my own work
  1787. 1:18:00I've stayed away from it somewhat
  1788. 1:18:03wimping out saying this is kind of
  1789. 1:18:05difficult and and messy and I I haven't
  1790. 1:18:08dealt with it. But I think it must have
  1791. 1:18:10to do with the fact that the technical
  1792. 1:18:13progress is not constant over a very
  1793. 1:18:15long horizon in manufacturing and that
  1794. 1:18:18the nature of the manufacturing goods
  1795. 1:18:19that you consume and how much you want
  1796. 1:18:21of it changes over time. Right? Think
  1797. 1:18:23about it. You're very poor in
  1798. 1:18:24agriculture. You want some basic
  1799. 1:18:26furniture, you want some basic housing
  1800. 1:18:28and everybody goes into that. Now we sit
  1801. 1:18:31in big houses. We have everything. You
  1802. 1:18:32want a somewhat better computer,
  1803. 1:18:34somewhat better car. maybe you want some
  1804. 1:18:37services much more than the additional
  1805. 1:18:40manufactured goods. So I think that's
  1806. 1:18:42what essentially the preferences that
  1807. 1:18:44are flexible capture and my hunch is
  1808. 1:18:47that drives it but I'm not an expert on
  1809. 1:18:49that question but it's again the second
  1810. 1:18:51excellent question Jingle
  1811. 1:18:54thank you
  1812. 1:18:55anybody
  1813. 1:18:57may question so uh I was uh wondering so
  1814. 1:19:02as the GDP per capita increases
  1815. 1:19:06uh do poor countries move to
  1816. 1:19:09manufacturing before they move new
  1817. 1:19:11services or is it like uh like if we go
  1818. 1:19:15from very less to very high can we
  1819. 1:19:17directly hit manufacturing and jump into
  1820. 1:19:21services?
  1821. 1:19:22Sorry I had some trouble getting the
  1822. 1:19:25connection. Can you ask the question
  1823. 1:19:26again please?
  1824. 1:19:28Sure. Uh I was asking if the GDP per
  1825. 1:19:31capita increases uh does a exaculture
  1826. 1:19:34heavy economy
  1827. 1:19:36does it can it move from exulture to
  1828. 1:19:40services directly or is that translation
  1829. 1:19:43always through manufacturing?
  1830. 1:19:47If I understand correctly and I
  1831. 1:19:48apologize if I don't because there was
  1832. 1:19:50some disturbances in the in the
  1833. 1:19:53connection. If I understand correctly,
  1834. 1:19:56there are exceptions where economies
  1835. 1:19:58have not developed the manufacturing
  1836. 1:20:00sector as much as others and jump to
  1837. 1:20:03services directly. I don't know where
  1838. 1:20:06you are from but this is sometimes
  1839. 1:20:08something people say about India
  1840. 1:20:12that the service sector is unusually
  1841. 1:20:14large in India compared to the average
  1842. 1:20:18um experience
  1843. 1:20:20and the manufacturing sector is not so
  1844. 1:20:22large. Now if you want to understand
  1845. 1:20:24developments like this, one way to think
  1846. 1:20:27about it is that in Germany where I come
  1847. 1:20:30from the manufacturing sector is still
  1848. 1:20:32unusually large although we are fairly
  1849. 1:20:34developed and the reason is we are just
  1850. 1:20:35pretty good at producing cars and
  1851. 1:20:37machinery and equipment and we export a
  1852. 1:20:40lot of it.
  1853. 1:20:42In other countries like Britain which is
  1854. 1:20:44at a similar level of development with
  1855. 1:20:48all due respect they're not very good at
  1856. 1:20:50producing cars. I had one once. I will
  1857. 1:20:52never buy one again. And they don't
  1858. 1:20:53exist anymore. And if they exist,
  1859. 1:20:55they're run by German companies. So
  1860. 1:20:57their manufacturing sector is relatively
  1861. 1:20:59small, but they have the city of London,
  1862. 1:21:02right? So they export a lot of financial
  1863. 1:21:04services. They are very good at this. We
  1864. 1:21:06are not so good at this. If you ever
  1865. 1:21:07been to Frankfurt, you know why. It's
  1866. 1:21:09kind of a boring dull place.
  1867. 1:21:12And we don't have a comparative
  1868. 1:21:13advantage in that. So if you take trait
  1869. 1:21:16into account which I've completely
  1870. 1:21:17blocked out here you can get fairly
  1871. 1:21:21sizable deviations from the average
  1872. 1:21:23behavior
  1873. 1:21:24right because you don't have to produce
  1874. 1:21:26every let me put it differently to you I
  1875. 1:21:29assumed that everything that you consume
  1876. 1:21:31you have to produce yourself
  1877. 1:21:34with trade that's not the case and so
  1878. 1:21:36with trade the consumption composition
  1879. 1:21:38may differ to a sizable extent from the
  1880. 1:21:41production composition now this is an
  1881. 1:21:43insight that can Inori Matsuyama had
  1882. 1:21:46about 15 years ago
  1883. 1:21:48and again it's something that's not in
  1884. 1:21:51the benchmark model but that's important
  1885. 1:21:53to think about and there's some work on
  1886. 1:21:55that where people uh Kui comes to mind
  1887. 1:21:58in the journal monetary economics 2013
  1888. 1:22:00has a nice paper on that but that's
  1889. 1:22:03that's a good question if that was your
  1890. 1:22:04question I hope I didn't butcher it and
  1891. 1:22:07it's an important question
  1892. 1:22:08yeah that was my question so yeah I was
  1893. 1:22:11thinking about uh yeah I I'm from India
  1894. 1:22:14And I was thinking about India and I was
  1895. 1:22:16also thinking about the comparative
  1896. 1:22:18advantage uh sign. So yes. Yeah.
  1897. 1:22:24Um could I ask something about uh
  1898. 1:22:28nesting this model in sort of an
  1899. 1:22:29international
  1900. 1:22:30Can you speak up a little bit Holt?
  1901. 1:22:32Sorry. Could I could I ask something
  1902. 1:22:33about putting this into into an
  1903. 1:22:35international framework? It kind of
  1904. 1:22:36builds on something that uh was being
  1905. 1:22:38said in the comments, but uh all of
  1906. 1:22:40these models have just exogenous TFP
  1907. 1:22:43growth. But if you look at the current
  1908. 1:22:45situation where some countries clearly
  1909. 1:22:47have much higher productivity, let's say
  1910. 1:22:49in agriculture than others, what are
  1911. 1:22:51some of the barriers that keep countries
  1912. 1:22:54with very low agricultural productivity
  1913. 1:22:56from essentially adopting the TFP of
  1914. 1:22:59much more agriculturally productive uh
  1915. 1:23:02regions?
  1916. 1:23:04I mean that's an excellent question
  1917. 1:23:06which is almost too excellent in the
  1918. 1:23:07sense that it goes way way beyond the
  1919. 1:23:10structural change model
  1920. 1:23:12and you're exactly right the structural
  1921. 1:23:14change model is a framework in which
  1922. 1:23:17I do not answer why TFP is what it is I
  1923. 1:23:21say given what TFP is what is the
  1924. 1:23:24composition of the economy so a whole
  1925. 1:23:27set of other questions and I think that
  1926. 1:23:29would be probably much more of an expert
  1927. 1:23:31in those than I am is Why are poor
  1928. 1:23:34countries
  1929. 1:23:35relatively
  1930. 1:23:37inefficient in doing agriculture? And
  1931. 1:23:40there's a huge literature gigia and many
  1932. 1:23:42others have contributed to that.
  1933. 1:23:46And it's I think we understand a little
  1934. 1:23:48more why that is.
  1935. 1:23:52There are certainly some barriers.
  1936. 1:23:54There's certainly human capital
  1937. 1:23:55differences.
  1938. 1:23:57There's the perils of subsistence
  1939. 1:24:01farming and inefficient use and
  1940. 1:24:03allocation of land to people. But I
  1941. 1:24:07don't want to go into the details of
  1942. 1:24:08that. First of all, I haven't prepared
  1943. 1:24:10for it. But it's also somewhat of a
  1944. 1:24:12separate issue. I like to think of what
  1945. 1:24:15determines TFP and then take TFP and ask
  1946. 1:24:18what determines the composition of the
  1947. 1:24:20economy as a result of TFP. And mine has
  1948. 1:24:22entirely been about the second question.
  1949. 1:24:25takes away it doesn't take away from the
  1950. 1:24:27first question being very interesting
  1951. 1:24:30but I have really nothing to say about
  1952. 1:24:32this here right I've assumed everything
  1953. 1:24:34is coming from heaven and it is what it
  1954. 1:24:36is and now let's see what happens
  1955. 1:24:40I think shar
  1956. 1:24:42ask a question
  1957. 1:24:42thank you
  1958. 1:24:45um prof so you um in the last part of
  1959. 1:24:49your section you make a lot of
  1960. 1:24:51recommendation on this paper and I think
  1961. 1:24:54one that resonates to an African
  1962. 1:24:56perspective in terms of um our structure
  1963. 1:25:00of the structural transformation is
  1964. 1:25:02industrial policy and there hasn't been
  1965. 1:25:05a lot of papers that do this work in um
  1966. 1:25:08in a theoretical format. So I was
  1967. 1:25:11thinking um of industrial policy in sort
  1968. 1:25:14of like a theoretical format uh and
  1969. 1:25:17looking at the consumption function that
  1970. 1:25:19you've put to ask if someone was to play
  1971. 1:25:21around with the consumption function and
  1972. 1:25:24particular on the manufacturing side and
  1973. 1:25:26probably um maybe allocate the constant
  1974. 1:25:30consumption somewhere um along that
  1975. 1:25:32manufacturing uh constant consumption.
  1976. 1:25:35would that also assist to probably ramp
  1977. 1:25:37up the efficiency in which the the
  1978. 1:25:42manufacturing sector operates because
  1979. 1:25:44industrial policy is quite an important
  1980. 1:25:47sector. I mean an important um factor in
  1981. 1:25:52in determining what happens uh within
  1982. 1:25:54growing the manufacturing sector in
  1983. 1:25:56Africa and we speak about a lot but we
  1984. 1:25:59have not tried to model that and include
  1985. 1:26:02it in the framework of structural
  1986. 1:26:04transformation. So uh perhaps can you
  1987. 1:26:07can I ask that you at least talk about
  1988. 1:26:09that a little and assist how does one
  1989. 1:26:11even try and include it in the models
  1990. 1:26:13that we're trying to work with here.
  1991. 1:26:14Thank you. And another excellent
  1992. 1:26:17question. I have to admit it's one that
  1993. 1:26:20I heard before. I gave uh essentially
  1994. 1:26:23this talk at an IMF training session
  1995. 1:26:26about 12 months ago and they asked me
  1996. 1:26:29exactly this question and I said it's a
  1997. 1:26:30great question. I have nothing to say
  1998. 1:26:32about it but we will work on it over the
  1999. 1:26:34summer. Well then the corona virus
  2000. 1:26:36happened and lots of other things
  2001. 1:26:37distracted me. I don't think I think
  2002. 1:26:40you're completely right Sharon. There's
  2003. 1:26:42not much work on that. This framework
  2004. 1:26:44cannot as it is tell you much about it
  2005. 1:26:47because it says given what the
  2006. 1:26:49productivities are what is the
  2007. 1:26:50composition but it doesn't say again and
  2008. 1:26:53this is related to hold as well where
  2009. 1:26:56the productivities come from if you want
  2010. 1:27:00to think about industrial policy that's
  2011. 1:27:02the focus of the analysis and we have
  2012. 1:27:05very little on that we tried to make
  2013. 1:27:07some progress and we got stuck I can
  2014. 1:27:09only say uh um Richard Akosh and I have
  2015. 1:27:12agreed to meet again in April and that
  2016. 1:27:14will be the subject about we think
  2017. 1:27:16namely
  2018. 1:27:18um what types of policies
  2019. 1:27:21are interesting to consider in these
  2020. 1:27:23models. Now notice one thing the
  2021. 1:27:25equilibrium of the model that I have
  2022. 1:27:27characterized is efficient. There is no
  2023. 1:27:29room for policy here therefore to
  2024. 1:27:32improve it.
  2025. 1:27:34So what that means is I have a model
  2026. 1:27:36that fits the data
  2027. 1:27:39but the government should stay out of it
  2028. 1:27:40given this model. Now I'm not thinking
  2029. 1:27:43that uh necessarily that industrial
  2030. 1:27:46policy is bad and should always be
  2031. 1:27:49avoided. I'm just saying this model
  2032. 1:27:50cannot speak about it to it at all. So I
  2033. 1:27:53agree with you Sharon bleak situation
  2034. 1:27:57but that's one subject on which you
  2035. 1:28:00could focus and I think it's an
  2036. 1:28:02important subject because in the
  2037. 1:28:03practical world if you talk to the IMF
  2038. 1:28:05guys that's all they care about. If you
  2039. 1:28:07tell them the world is efficient the
  2040. 1:28:09next conclusion is why are you here?
  2041. 1:28:11your rent because you don't do anything
  2042. 1:28:13good. They don't like that conclusion,
  2043. 1:28:15you know, by the fact that they make a
  2044. 1:28:16lot of money. They think they're
  2045. 1:28:17important. Therefore, you have to write
  2046. 1:28:19a model in which they are important to
  2047. 1:28:20speak to them. And we are going to try
  2048. 1:28:22and do that because I want to get
  2049. 1:28:24invited again to the IMF.
  2050. 1:28:27Listen, I'm going to intervene here
  2051. 1:28:28because I know that Berthold um has in
  2052. 1:28:33fact an important appointment to get to
  2053. 1:28:35and I just want to thank you, Berthold.
  2054. 1:28:37I wonder if those of you in the front
  2055. 1:28:38row um would be willing to unmute your
  2056. 1:28:41microphones and so that we can give
  2057. 1:28:43Berthold a kind of old-fashioned round
  2058. 1:28:45of applause out loud. And uh just thank
  2059. 1:28:49you again, Berthold, for making the time
  2060. 1:28:51and for and for a great and clear
  2061. 1:28:53lecture.
  2062. 1:28:55Thank you. That's an impressive round of
  2063. 1:28:57applause. It was a pleasure.
  2064. 1:28:59I like the I like the icon, the applause
  2065. 1:29:01icon, but it doesn't resonate in quite
  2066. 1:29:03the same way. and thank you again for
  2067. 1:29:06the time. Um, I'll pass along your
  2068. 1:29:09comments about the British automaking
  2069. 1:29:11industry. Um,
  2070. 1:29:15and I want to thank everyone for taking
  2071. 1:29:18part for the questions from the front
  2072. 1:29:20row for the questions from everyone um,
  2073. 1:29:24in the Q&A. We're trying to figure out a
  2074. 1:29:27way to post the Q&A content along with
  2075. 1:29:30the slides and other things um on the
  2076. 1:29:33website and to provide as much of the
  2077. 1:29:35material as we can. But Berthold, thank
  2078. 1:29:37you so very very much and great
  2079. 1:29:40appreciation to you. I would also like
  2080. 1:29:42once again to thank uh Mandy and Kirsty
  2081. 1:29:46and Lauren and the team at CR for
  2082. 1:29:49putting this together and for sticking
  2083. 1:29:50around late on a Friday evening. So many
  2084. 1:29:54thanks and uh we look forward to seeing
  2085. 1:29:56you all next week when we continue on
  2086. 1:29:59and um for those of you in the front row
  2087. 1:30:02who are going to be available um for the
  2088. 1:30:05TA session on Monday, we look forward to
  2089. 1:30:07seeing you there. Couple of people
  2090. 1:30:09commented in the Q&A. We really haven't
  2091. 1:30:11figured out a good way to do the to make
  2092. 1:30:14the TA sessions available for we're kind
  2093. 1:30:17of wrestling with the challenge that a
  2094. 1:30:20TA session is necessarily small and we
  2095. 1:30:23haven't quite figured out a way to
  2096. 1:30:25provide more than basic content. So
  2097. 1:30:28we'll keep working on that and see what
  2098. 1:30:29we can do. But um again thanks to
  2099. 1:30:32everyone and we look forward to your
  2100. 1:30:34feedback. Please let us know if there's
  2101. 1:30:36if you have comments or feedback for us.
  2102. 1:30:38Just one question.
  2103. 1:30:40One, one last question. So, is the TA
  2104. 1:30:43session also going to be posted the
  2105. 1:30:45video so that those who can't attend it
  2106. 1:30:47can see it?
  2107. 1:30:48I I think um I think that's a question
  2108. 1:30:51for Santi and also for the participants
  2109. 1:30:53themselves. We don't want to smother
  2110. 1:30:54participation
  2111. 1:30:56um if people are nervous about having
  2112. 1:30:57their questions um going to the world.
  2113. 1:31:00But maybe that's something we can figure
  2114. 1:31:02out.
  2115. 1:31:03I mean, it would be nice for those who
  2116. 1:31:04are excluded if they want to see what he
  2117. 1:31:07said. agree.
  2118. 1:31:08I don't know. I want to I haven't talked
  2119. 1:31:09to Santi. But knowing him is
  2120. 1:31:10well on on my end you have Yeah. You
  2121. 1:31:13have the approval. So if you want to do
  2122. 1:31:15it and the participants agree with that
  2123. 1:31:16then we are
  2124. 1:31:18All right. Well, we'll try to sort that
  2125. 1:31:19out before before we go live and we'll
  2126. 1:31:21let people know.
  2127. 1:31:23But thank you all.
  2128. 1:31:24Okay. Thank you very much and have a
  2129. 1:31:27nice day. Bye bye.
  2130. 1:31:28Bye. And thanks again, Bert.

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