Category: Education

Teaching Modern Principles Online

I’ve been teaching hundreds of students the principles of economics using Modern Principles of Economics and its online course management system and the response has been excellent. Most students like the class but what always surprises me is that some students like the online class better than any other class they have ever taken. A good lesson about different learning styles. Some reviews:

  • I wanted to say thank you for the way you teach your class. I just started it and it is way better than I expected. The videos you made are why I’m thanking you. In high school I would always have to go home and watch videos explaining what the teacher taught us….your class is already the best class I have taken in my life because it fits the way I learn. I’ve never really written an email like this so forgive me if it breaks the usual business casual email approach. Thank you again!
  • I am a student a George Mason…I would like to say that these classes are the best online classes I have taken and wish all my classes would be like this! Especially with Mason being mostly online and all of my classes being online this semester, I think that this class’s design should be an outline for other online classes. The videos themselves are very well edited and can be fun to watch! Instead of just watching a PowerPoint online and taking notes, being able to see the professor speak, while incorporating graphs, and even animations makes the class much more enjoyable, and in my case easier to absorb. Another aspect I wish all online classes did is giving quizzes along with the videos to check information learned. Speaking from my experience in your previous class the “Learning Curve” and other pre-test activities did wonders for me when preparing for chapter tests and exams. Overall, these classes are a great experience and I look forward to this semester in Econ 104! As a little side note, my favorite videos/lessons from last semester where the ones where you and Professor Cowen would debate over subjects learned in class. It gave useful insight and thinking to both sides of the argument.
  • I really liked how it was set up with the videos. As someone who has diagnosed ADHD, this type of online class, and class in general has made it so much easier for me to constantly go back on videos to hear what the professors were saying and trying to teach us. Honestly best class experience I’ve ever had, and I wish more were like it.
  • Prof. Tabarrok’s videos that accompanied our course material were of high quality. Even though this was a distance learning course, I felt that I got an in depth lecture for each section of the course. I did not feel that I was left to read the book myself; it was like I had great in-person lecture that I could re watch again and again.
  • Since this is an online course, I expected it to be very short cut and not interactive. This course was the total opposite. Being able to watch videos about professors genuinely teaching economics and answering questions while following the video was so helpful.The aspects of the course allowed me to connect with different imperative issues & solutions across the world.

Who Mismanages Student Loans and Why?

From Kimberly Rodgers Cornaggia and Han Xia:

With a license to use individually identifiable information on student loan borrowers, we find that a majority of distressed student borrowers manage their debt sub-optimally and that suboptimal debt management is associated with higher loan delinquency. Cross-sectional analysis indicates that loan (mis)management varies significantly across student gender, ethnicity, and age. We test several potential selection-based explanations for such demographic variation in student loan management, including variation in students’ overconfidence, consumption preferences and discount rates, and aversion to administrative paperwork. Motivated by federal and state allegations against student loan servicers, we also test for the presence of treatment effects. Overall, the empirical evidence supports the conclusion that loan servicers’ differential treatment across borrowers play an important role in student loan outcomes.

Here is a key background fact:

Broadly, subsidized student borrower assistance programs include provisions for loan forbearance, loan deferment, and
income-driven repayment (IDR) options for financially distressed borrowers.

Borrowers should switch to those provisions more than they do, with older students, non-traditional students, males, and non-whites performing less well than others.  Here is the link to the paper, via the excellent Kevin Lewis.

My podcast with Darren Lipomi

He is a well-known chemist (and more) at UC San Diego. We started with classic Star Trek and then moved into textiles, chemistry, music vs. sound, nanobots against Covid, how to interview, traveling during a pandemic, art collecting and voodoo flags, the importance of materials science, and much more.  Mostly he interviewed me, though it went a bit both ways.

Almost 100% fresh material and topics, and here is the Spotify link.

MIT graduate micro exam, 1961

From the archives of Irwin Collier (I won’t do any extra indentation):

Economics Candidates: Answer any FOUR questions (thirty minutes each).
S.I.M. Candidates: Answer any TWO questions (thirty minutes each).

  1. Within the framework of static, partial-equilibrium theory, indicate under what circumstances advertising will reduce product prices in the long run, (a) if the advertiser is a simple monopolist, (b) if the advertisers are members of a large, perfectly symmetrical, Chamberlinian group of suppliers of differentiated products (the number of firms being large enough to rule out oligopolistic relationships, and variable in accordance with a long-run-equilibrium condition of zero profit for all firms).
  2. How is a firm’s demand schedule for a particular factor of production derived (a) when that factor is the only variable one, and (b) when the quantities of all factors are variable? Show which of these demands is, if anything, the more elastic.
  3. The demands for two products are: q1 = q2 = 54 – p1 -p2. How would you characterize their relationship? If they are produced by separate sellers at constant average costs of c1 = 12 and c2 = 6, respectively, calculate each man’s equilibrium price, quantity, and profit under each of the following conditions:
    1. Each seller assumes that the other’s price is a constant;
    2. The second seller behaves that way and the first seller realizes that he does;
    3. Both sellers maximize their joint profit and share it equally.
  4. Two countries can produce food (F) and clothing (C) with labor (L) as the only factor of production. Country A has 20 billion units of L, each of which can produce either 5 units of F or 2 units of C. Country B has 10 billion units of L, each of which can produce either 8 units of F or 6 units of C. Everyone always spends half of his income on F and the other half on C. In a purely competitive equilibrium with balanced trade between the two countries (and no transportation costs), what is the effect on the quantities of F and C produced and consumed in each country? Could either country benefit by imposing a tariff on the imported good?
  5. What are the various reasons why a free-private-enterprise economy may fail to allocate its resources in an optimally efficient way? Explain.
  6. Discuss the roles of “real” and “monetary” elements in a satisfactory theory of interest. Is it logically possible to fashion an interest theory exclusively in terms of one or the other of those elements? Explain.

TC again: I don’t think current graduate students (outside of MIT and a few other places) would do very well on #1, nor do I think they would understand what is being asked on #6, much less have a good answer.  On #5, I wonder how many would give a sufficiently analytical answer rather than just repeating a bunch of cliches from media and social media?

What should I ask Benjamin M. Friedman?

As noted, Ben has a new and very interesting book coming out Religion and the Rise of Capitalism.  He is also the author of the superb The Moral Consequences of Economic Growth, and the earlier Day of Reckoning, about the economic policies of the Reagan administration.  Ben has been a leading macroeconomist since the 1970s, and he taught me Ph.D. macro at Harvard in 1984, one of my favorite professors I might add.  Here is Ben on

So what should I ask him?

International Trade in Modern Principles

The Trump tariffs are the biggest change in trade policy since Smoot-Hawley. Whatever the economic merits of the Trump tariffs, they make great material for textbook authors! As we illustrate in the new edition of Modern Principles, drawing on a great paper by Flaaen, Hortaçsu and Tintelnot. The excerpt illustrates our approach throughout our textbook, Modern Principles, modern applications.


Now that you know how to analyze international trade using demand and supply, let’s see how well the theory holds up by looking at what happened in the market for washing machines after the Trump tariffs were put into place in January of 2018. The tariff came in two parts. The first 1.2 million washing machines were taxed at a rate of 20% and all remaining imports were taxed at a rate of 50%. The tariffs were put in place for three years with slight declines (to 18% and 45% and 16% and 40%) in the 2nd and 3rd year respectively. A 50% tariff on washing machine parts was also included to prevent manufacturers from avoiding the duty by shipping parts to the United States for quick assembly.

Before the tariffs were put into place, about 3.8 million washing machines were imported per year. Once the tariffs began, imports declined by 1.2 million units to approximately 2.6 million washing machines per year. Figure X shows the price index for laundry equipment in the United States. Prices for washer and dryers had been declining since at least 2013, but the moment tariffs were imposed prices jumped dramatically. (Slight declines in prices were also seen in 2019 when the tariff rate decreased modestly).

Economists estimate that the tariff increased the price of washing machines by about 12%. That’s actually a smaller increase in price than one might guess from the size of the tariff but it turns out that dryer prices also increased by about 12%. Dryers were not subject to the tariff. So why did dryer prices increase? Washers and dryers are typically bought together in a package. Manufacturers, therefore, tend to focus on the package price and they “smoothed” out the washer tariff over both washers and dryers. Looking at thousands of goods, economists estimated that the Trump tariffs were on average entirely passed on to consumers, just as the simple supply and demand model predicts.

Another important prediction of the supply and demand model is that the tariff will increase the prices of all washing machines, whether produced domestically or imported. When the tariff is first put into place, domestic producers have lower costs than foreign producers and, as a result, they sell more and increase output. As domestic producers increase their output, however, their costs rise until in equilibrium domestic and foreign producers are, once again, selling for the same price. In fact, this is exactly what happened. Domestic producers like Whirlpool raised their prices at least as much as did foreign producers.

The Trump tariffs did have one unexpected consequence. In the model, it’s natural to think of domestic producers as being domestically owned firms, but that is not necessarily the case. Whirlpool, a domestic producer of washing machines, did produce more because of the tariffs but something else happened. The foreign producers, Samsung and LG, expanded their US factories! That’s good for US workers in the washer and dryer industry. Nevertheless, the expansion of Samsung and LG was probably an unwelcome surprise to Whirlpool, which may have expected that the tariffs would give them more of a competitive advantage in the domestic market than they ended up getting.

The increase in domestic production from both domestically owned and foreign owned firms resulted in about 1800 new jobs in the washer and dryer industry. Remember trade policy does not influence the total number of jobs in an economy. The jobs created in the washer and dryer industry came at the expense of jobs lost in US export industries. The new jobs in the protected industry, however, are visible and they are important politically, because the President can point to them as a benefit of his policies. Thus, it’s an interesting question to ask, how much did consumers pay to create these jobs?

The tariffs increased washer and dryer prices by about 12% or $88 each on combined sales of 17.4 million units. The total cost to consumers, therefore, was approximately $1.56 billion per year. The government took in an extra $82.2 million in tariff revenues, which we count as a plus, so the total cost was about $1.46 billion per year. The cost per job created was therefore a whopping $811,000 per job (1.46 billion/1800). Instead of creating jobs by paying more for washers and dryers, US consumers would have been much better off paying each new worker in the laundry industry $100,000 to enjoy a nice vacation!

My Conversation with Jimmy Wales

It was excellent throughout, here is the audio, video, and transcript, here is part of the summary:

Jimmy joined Tyler to discuss what happens when content moderation goes wrong, why certain articles are inherently biased, the threat that repealing section 230 poses to Wikipedia, whether he believes in Conquest’s Law, the difference between “paid editing” and “paid advocacy editing,” how Wikipedia handles alternative accounts, the right to be forgotten, his unusual education in Huntsville, Alabama, why Ayn Rand is under- and over-rated, the continual struggle to balance good rules and procedures against impenetrable bureaucracy, how Wikipedia is responding to mobile use, his attempt to build a non-toxic social media platform, and more.

Here is an excerpt:

COWEN: I’m the rare person who actually has no sock puppets. Why not allow sock puppets? What exactly is wrong with them? So what if a person has more than one identity out there, as long as you can monitor the identity that is operating on Wikipedia?

WALES: That’s a great question. In fact, we do try to make a distinction between a sock puppet and a legitimate alternate account. We actually have procedures whereby you can declare a legitimate alternate account to the arbitration committee so that you’re insulated from any bad harms if it’s found out. Some of the keys are that we rely on trust.

One of the things that is really important to us — we do a lot of what we call “not voting.” It’s voting, but it’s really a straw poll. The votes — typically, they’re not the final word, and if somebody comes into a discussion and pretends to be five different people, arguing that something should be deleted, and there are two actual different people arguing that it should be kept, that’s deceptive. It kind of skews the balance.

People who are reviewing that say, “Well, I think we should keep it, but I see there are five people here with a different opinion, so maybe I’m wrong.” That bulking up your impact by double-voting on something, by pretending to be different people, is super problematic.

The other problematic sock puppeting is a sock puppet to conceal your conflict of interest. I remember we had one notorious case of a PR firm that had engaged in quite a lot of problematic editing.

One of their accounts — it made a lot of edits and pretended to be a retired fellow who was a car collector. There were all these pictures of old cars and so on. They had a whole persona created that seemed like a lovely chap who just liked to edit Wikipedia, but in fact, it was just somebody at the PR firm who was giving a cover, and I think that kind of deception is problematic.

The good examples of multiple accounts would be someone who wants to edit in a controversial area. As an example, let’s say you’re a well-known person, and suppose you took an interest in our entries on pedophilia, not because of any prurient interests but simply because you think this is actually an important topic of social impact.

Well, you probably wouldn’t necessarily want to be known at your university as the guy who edits the pedophilia articles on Wikipedia. That’s just not easy for people to be open about, even if you’re doing all the right things. So you might say, “Yes, I actually want to edit in some areas of World War II history under this identity, but I’m going to do some work over here, and I really prefer it not to be tied back to my real-life identity.” And that’s kind of okay, as long as you’re not voting in elections with two accounts and things like that.

Definitely recommended.

Platform Economics in Modern Principles

Why is Facebook free? Why are credit cards less than free? Why do singles bars sometimes have women drink free nights but never men drink free nights? All of these questions are in the domain of platform economics. Platform economics is new. Tirole and Rochet practically invented the field with a seminal paper in 2003–and that paper was one of the reasons Tirole won the Nobel prize in 2014. Despite being new, platform economics deals with goods which are fundamental to the modern economy. Thus, Tyler and I thought that it was incumbent upon us to teach some of the intuition behind platform economics in Modern Principles of Economics. But students have enough new material to learn, so we set ourselves a challenge–explain the intuition of platform economics using principles that the students already know. Surprisingly, platform economics can be taught with just two principles: externalities and elasticities.

In our chapter on externalities we offer the students a puzzle. Why do some firms offer their workers free flu shots? The answer, as memorably illustrated in this video, is that the firm “internalizes the externality.” When one worker gets a flu shot, other workers at the firm are less likely to get sick. In principle, the workers could subsidize one another to achieve the efficient outcome but transactions costs makes that solution impractical (the Coase theorem). The firm, however, is already involved in transactions with all the workers and, as a result, it can subsidize flu shots and reap the benefits of workers taking fewer sick days. How much the firm should subsidize flu shots depends on the elasticity of flu shots with respect to the price and on the elasticity of sick days with respect to vaccinated workers.

Now what does this have to do with Facebook? Well think about seeing ads as a bit like getting a flu shot–seeing ads has a benefit to you but it’s also a bit of a pain so if you had a choice you might not watch that many ads. But advertisers want you to see ads–in other words, Facebook users who see ads create a positive externality for advertisers. The platform firm, Facebook, internalizes this externality and that means subsidizing ad-seeing by selling Facebook at a zero price to readers and instead charging advertisers. As we put it in Modern Principles:

Imagine that Facebook begins with a positive price for both readers and advertisers (PR>0 and PA>0). Readers, however, are likely to be sensitive to the price so a small decrease in price will cause a large increase in readers (very elastic demand). Thus, imagine that Facebook lowers the price to readers and thus increases the number of readers. With more readers, Facebook can charge its advertisers more, so PA increases. Indeed, if the demand for advertisers increases enough, it can even pay Facebook to lower the price to readers to zero! Thus, the key to Facebook’s decision is how many more readers it will get when it lowers the price (the reader elasticity), how much those readers are worth to advertisers (the externality of readers to advertisers) and how high can it increase the price to advertisers (the advertiser elasticity).

More in the textbook!

Modern Principles, New Edition!

The new edition of Modern Principles is here! We take our title, Modern Principles of Economics, seriously. Other textbooks stick with the market for ice cream year after year but when it comes to new editions we don’t just add a box or two–we rewrite entire chapters with new examples and applications and we cut older material to make way for the new.

In the new edition we introduce platform economics and we use it to explain why Facebook is free; we have new material applying the elasticity of supply to understand why housing is so expensive in some cities; we have rewritten the chapter on trade to take into account the China shock and the China trade-war shock including the implications for politics; we have new material on pollution and a carbon tax; new material on the declining labor force participation rate of men and new material on supply chains and bottlenecks. Of course, there is also new material on pandemics although we had material on pandemics in the very first edition!

Modern Principles of Economics is by far the best textbook for teaching online (or offline!). Not only do you get over a hundred professionally produced videos, like this one on price ceilings and price coordination, you also get Achieve, the excellent new course management system that integrates e-book, tutorials, quizzes, exams, assessment and much more so that you can get up and running online overnight.

I’ll be covering some of the new material in Modern Principles this week.

Is AI centralizing research influence?

Increasingly, modern Artificial Intelligence (AI) research has become more computationally intensive. However, a growing concern is that due to unequal access to computing power, only certain firms and elite universities have advantages in modern AI research. Using a novel dataset of 171394 papers from 57 prestigious computer science conferences, we document that firms, in particular, large technology firms and elite universities have increased participation in major AI conferences since deep learning’s unanticipated rise in 2012. The effect is concentrated among elite universities, which are ranked 1-50 in the QS World University Rankings. Further, we find two strategies through which firms increased their presence in AI research: first, they have increased firm-only publications; and second, firms are collaborating primarily with elite universities. Consequently, this increased presence of firms and elite universities in AI research has crowded out mid-tier (QS ranked 201-300) and lower-tier (QS ranked 301-500) universities. To provide causal evidence that deep learning’s unanticipated rise resulted in this divergence, we leverage the generalized synthetic control method, a data-driven counterfactual estimator. Using machine learning based text analysis methods, we provide additional evidence that the divergence between these two groups – large firms and non-elite universities – is driven by access to computing power or compute, which we term as the “compute divide”. This compute divide between large firms and non-elite universities increases concerns around bias and fairness within AI technology, and presents an obstacle towards “democratizing” AI. These results suggest that a lack of access to specialized equipment such as compute can de-democratize knowledge production.

That is a new paper by Nur Ahmed and Muntasir Wahed.

School choice in Los Angeles

By Christopher Campos and Caitlin Kearns have some very positive results on school vouchers:

This paper evaluates the Zones of Choice (ZOC) program in Los Angeles, a school choice initiative that created small high school markets in some neighborhoods but left traditional attendance zone boundaries in place throughout the rest of the district. We leverage the design of the program to study the impact of neighborhood school choice on student achievement, college enrollment, and other outcomes using a matched difference-in-differences de-sign. Our findings reveal that the ZOC program boosted test scores and college enrollment markedly, closing achievement and college enrollment gaps between ZOC neighborhoods and the rest of the district. These gains are explained by general improvements in school effectiveness rather than changes in student match quality, and school-specific gains are concentrated among the lowest-performing schools. We interpret these findings through the lens of a model of school demand in which schools exert costly effort to improve quality.The model allows us to measure the increase in competition facing each ZOC school based on household preferences and the spatial distribution of schools. We demonstrate that the effects of ZOC were larger for schools exposed to more competition, supporting the notion that competition is a key channel driving the impacts of ZOC. In addition, demand estimates suggest families place a larger weight on school quality compared to peer quality, providing schools the right competitive incentives. An analysis using randomized admission lotteries shows that the treatment effects of admission to preferred schools declined after the introduction of ZOC, a pattern that is explained by the relative improvements of less-preferred schools. Our findings demonstrate the potential for public school choice to improve student outcomes while also underscoring the importance of studying market-level impacts when evaluating school choice programs.

Here is a link to the paper, note that Christopher is on the job market this year from UC Berkeley.

Secularization and the Tribulations of the American Working-Class

That is a work in progress by Brian Wheaton, job market candidate from Harvard University.  Here is the abstract:

Over the past several decades, working-class America has been plagued by multiple adverse trends: a sharp increase in social isolation, an even sharper increase in single parenthood, a decline in male labor force participation rates, and a decline in generational economic mobility – amongst other things.  Material economic factors have been unable to fully explain these phenomena, often yielding mixed results or – in some cases, such as that of single parenthood – lacking explanatory power altogether.  I study the decline in religiosity and, using a shift-share instrument leveraging the fact that different religious denominations are declining at different rates, I find that religious decline has a strong adverse effect on the aforementioned variables.  The effects are not weakened by including other potential explanatory factors (such as China trade shocks and variation in public assistance).  I present evidence that, to the extent reverse causality exists, it creates bias in the opposite direction of my estimates.  These findings are also robust to several alternative instruments, including the repeal of the state blue laws banning retail activity on Sundays and the Catholic church scandals of the 2000s.  Two instruments – the blue laws and the state anti-evolution laws mandating teaching of creationism in school – allow me to ascertain whether the effect proceeds through religious attendance or beliefs.  I find that, for most outcomes, the bulk of the effect is driven by religious attendance.

To be clear, that is not Brian’s job market paper, which covers “Laws, Beliefs, and Backlash.” Or you might wish to try these results on corporal punishment in schools (with Maria Petrova and Gautam Rao):

We find that the presence of corporal punishment in schools increases educational attainment, increases later-life social trust and trust in institutions, and leads to less authoritarian attitudes toward child-rearing, and greater tolerance of free speech. Additionally, exposure to corporal punishment in school decreases later-life crime. We find no effects on mental or physical health.

Here is his paper about flat tax reform in Eastern Europe:

Using static and dynamic difference-in-differences approaches, I find that the flat tax reforms increase annual GDP growth by 1.36 percentage points for a transitionary period of approximately one decade.

I praise the scholarship and courage of Brian N. Wheaton.

My Conversation with Edwidge Danticat

Here is the audio, video, and transcript.  Here is the CWT summary:

She joined Tyler to discuss the reasons Haitian identity and culture will likely persist in America, the vibrant Haitian art scenes, why Haiti has the best food in the Caribbean, how radio is remaining central to Haitian politics, why teaching in Creole would improve Haitian schools, what’s special about the painted tap-taps, how tourism influenced Haitian art, working with Jonathan Demme, how the CDC destroyed the Haitian tourism industry, her perspective on the Black Lives Matter movement, why she writes better at night, the hard lessons of Haiti’s political history, and more.

Here is one excerpt:

Recommended.  And I thank Carl-Henri Prophète for assistance with the transcription.

Christina Romer!

Christina Romer is excellent in this video on her work and influence. Obama had a great line. When Romer, clearly upset, told Obama that the economy was much worse than expected and heading downwards he replied, “Christy, it’s not your fault….yet.”

An interesting tension in Romer’s work. Her early work suggests that macroeconomic policy has not done much to stabilize the economy. Yet her later work has been in trying to stabilize the economy!