Are Economists Japan's New Exports?

I created a list of Japanese economists who currently work at universities outside of Japan: Link.

Although the list is still incomplete (it may never be complete), the number of economists has already reached 100! This is far beyond my expectation!! And so, making the list has taken much longer time than I expected...

As you might know, getting an academic job at a good research university is very difficult, even if you have a Ph.D. from a top school. The list shows that Japanese economists, especially among the young generation (those graduated their colleges in the late 90's or later), are highly competitive. In recent years, it is not uncommon for Japanese junior economists to get international academic jobs posted in the JOE.

I wish my list help visualizing the great success of overseas Japanese economists, and stimulate domestic Japanese economists as well. By the way, a list of Japanese economists who work at domestic universities (with reasonably good research outputs) is now in preparation. Don't miss it!


Samurai in Brazil

Another cool TV commercial was made by CUPNOODLE. The Samurai in the movie is Kotaro TOKUDA, the world champion of the freestyle football!


Special CM featuring #10

A special TV commercial made by KIRIN BEER was broadcasted only on May 31, the last day of National Stadium (国立競技場). This CM features a Japanese football player Shinji Kagawa, the number 10 of our national team, whom I believe makes a big surprise in the FIFA world cup :) Go Shinji! Go Japan!!


Athey et al. (2005)

Original article (link) posted: 07/11/2005

Athey, Atkeson and Kehoe (2005) "The Optimal Degree of Discretion in Monetary Policy" Econometrica

The paper examines a monetary policy game in which the monetary authority has private information about the state of the economy. In the literature, two seminal papers, Taylor (1983) and Canzoneri (1985), established no discretion should be left to the monetary authority if there is no such private information; the best outcomes can be achieved by rules that specify the action of the monetary authority as a function of observables. The introduction of private information creates a tension between discretion and time inconsistency. Tight constraints on discretion mitigate the time inconsistency problem in which the monetary authority is tempted to claim repeatedly that the current state of the economy justifies a monetary stimulus to output. However, tight constraints leave little room for the monetary authority to time-tune its policy to its private information. In short, loose constraints allow the monetary authority to do that fine tuning, but they also allow more room for the monetary authority to stimulate the economy with surprise inflation.

Making use of dynamic mechanism design techniques, they find that the optimal mechanism is quite simple; for a broad class of economics, the optimal mechanism is static (policies depend only on the current report by the monetary authority) and can be implemented by setting an inflation cap, an upper limit on the permitted inflation rate. It is also shown that the optimal degree of monetary policy discretion turns out to shrink as the severity of the time inconsistency problem increases relative to the importance of private information.

The results they derive seem to be very interesting. In particular, the “inflation cap” result is directly related to the optimal inflation targets and has strong importance with actual monetary policies. As they mention, their work provides one theoretical rationale for the type of constrained discretion advocated by Bernanke and Mishkin (1997). This paper might become a must-read paper for those who work in monetary policies.

Bernanke and Mishkin (1997) "Inflation Targeting: A New Framework for Monetary Policy?" J. of Econ, Perspectives, 11
Canzoneri (1985) "Monetary Policy Games and the Role of Private Information" AER, 75
Taylor (1983) "Rules, Discretion, and Reputation in a Model of Monetary Policy: Comments" JME, 12


Echenique (2003)

Echenique, F. (2003), The Equilibrium Set of a Two Player Game with Complementarities is a Sublattice, Economic Theory, 22: 903-905.  Link 
Summary  I prove that the equilibrium set in a two-player game with complementarities, and totally ordered strategy spaces, is a sublattice of the joint strategy space.

It is widely known that in games with strategic complementarities (GSC), i.e., best reply correspondings are monotone increasing for all players, the set of pure-strategy Nash equilibria forms a non-empty complete lattice. This result implies the existence of smallest and largest Nash equilibria.

The current paper looks further into the structure of the equilibrium set of GSC, and shows that under certain restrictions the equilibrium set becomes not just a complete lattice but also a sublattice, as is written down in the Summary above.

The practical importance of this result, according to the author, is:
If the equilibrium set of a game is a sublattice, then we can find new equilibria from knowing that two profiles are equilibria, and by taking the componentwise join and meet of players’ strategies.

Note that we cannot obtain such strong property by a complete lattice structure alone. In this sense, a sublattice is indeed critical. The proof is extremely simple, which makes use of the observation that (a) when there are only 2 players and (b) their strategy spaces are completely ordered, (c) the other player's strategy must be completely ordered. The property (c) does not hold either (a) or (b) is not satisfied. Once (c) is verified, the rest of the proof is just to follow the definition of GSC.

My random thought: A sublattice property also arises in one-to-one two-sided matching markets (but neither in one-to-many nor many-to-many markets). I'm wondering if the idea of this paper can be somehow connected to the sublattice property of the set of stable matchings.

A final remark: A nicely written but a bit uninformative note.


Sotomayor (1996)

Sotomayor, M. (1996), A non constructive elementary proof of the existence of stable marriages, Games and Economic Behavior, 13: 135–7.  Link 
Abstract  Gale and Shapley showed in their well known paper of 1962 (Amer. Math. Monthly 69, 9–14) that stable matchings always exist for the marriage market. Their proof was constructed by means of an algorithm. Except for the existence of stable matchings, all the results for the marriage market which were proved by making use of the Gale and Shapley algorithm could also be proved without the algorithm. The purpose of this note is to fill out this case. We present here a nonconstructive proof of the existence of a stable matching for the marriage market, which is quite short and simple and applies directly to both cases of preferences: strict and nonstrict. 

In this short note, the author establishes the existence of stable matchings for the marriage market, i.e., one-to-one matching market, without employing any algorithms. Her key idea is a new concept that she calls a simple matching, which is defined as follows:
A matching is simple if, in the case a blocking pair (m, w) exists, w is single.

Since the set of simple matchings is nonempty and finite, there must exist a specific matching that I call here (for notational convenience) an M-simple matching:
A simple matching is M-simple if it cannot be (weakly) Pareto dominated for men by any other simple matching.

Then, she shows that such M-simple matching is stable. The basic logic is that the existence of blocking pair necessarily induces Pareto improvement for men (since w is single), which contradicts to the Pareto efficiency of M-simple matching for men.

As the author claims, the proof is very shout and simple, yet quite novel I think. To explain her proof strategy in a different way, she

  1. focuses on the subset of stable matchings
  2. characterize it by "M-simple matching," and
  3. shows that the set is non-empty. 

It is immediate that M-simple matching is unique and coincides with M-optimal stable matching when all the preferences are strict. In this way, we can see that her idea is somewhat related to the existence of one-sided optimal stable matchings, a widely known result in the literature.

A minor remark: The definition of matching in the paper incorporates individual rationality, and consequently that of of stable matchings pays attention only on blocking pairs. This looks a bit non-standard while nothing is lost in her analysis.

A final remark: I like this paper very much :)


How did GS algorithm come out?

Roth, A. (2008), Deferred acceptance algorithms: history, theory, practice, and open questions, International Journal of Game Theory, 36: 537-569.

In this survey article on the Gale-Shapley's deferred acceptance algorithm, Al Roth mentions (in footnote 3) an amazing story about how GS discovered the algorithm (which of course established the theory of two-sided matchings):

At his birthday celebration in Stony Brook on 12 July 2007, David Gale related the story of his collaboration with Shapley to produce GS by saying that he (Gale) had proposed the model and definition of stability, and had sent to a number of colleagues the conjecture that a stable matching always existed. By return mail, Shapley proposed the deferred acceptance algorithm and the corresponding proof


IO Seminar (Rysman)

Original article (link) posted: 04/11/2005

Gowrisankaran and Rysman "Dynamics of Consumer Demand for New Durable Consumer Goods"

The paper proposes a dynamic model of consumer preferences for new consumer durable goods and estimates it. Consumers in their model are heterogeneous. They are assumed to choose between purchasing a current product and waiting for future products, making rational forecasts about the future distribution of prices and qualities. Two actual industries, DVD players and digital cameras are estimated.

The model seems to be attractive because it examines dynamic aspects and heterogeneity of consumers that have not been done successfully in the literature, although everyone agrees the importance. I am bit wondering if incorporating the uncertain of the future markets has serious effects to the estimated results or not. In their model, consumers fully know when and what kind of products will appear. However, if the future market is uncertain in the sense that consumers only know the probability distribution of future products, there might be an additional waiting value. That is, consumers may be better off by postponing their purchase to resolve uncertainty. This option value of waiting is known as "Real Option" in finance. In real world, the arrival of new products typically depends on the result of R&D investments which is presumably stochastic. So, even firms cannot exactly know the schedule of future products in many cases. Therefore, to incorporate future uncertainty is an important extension I think.