Public investment criteria under optimal nonlinear income taxation without commitment

In this study, we highlight that the incredibility of the government's commitment to a certain tax policy is a determinant of production inefficiency. We show that if the government cannot commit to a certain tax policy and if the types of taxpayers are completely separated, then the production efficiency theorem could be violated in an optimal solution. In this case, an incremental unit of public or private capital affects taxpayers' labor supply through wage rates. In a situation where public capital is more (less) complementary to labor than private capital, public investment tightens (relaxes) the incentive compatibility constraint more than private investment.     

Collusion and heterogeneity of firms

We examine the impact of heterogeneous discounting on collusion in dynamic Bertrand competition. We show exactly when collusion can be sustained and how collusion would be organized efficiently with heterogeneous discounting. First, we show that collusion is possible if and only if the average discount factor exceeds a certain threshold, with or without capacity constraints. Next, we identify a dynamic pattern of market share that characterizes efficient collusion and obtain the unique long‐run prediction despite the presence of multiple equilibria. In the long run, the most patient firm and the most impatient firm tend to dominate the market.     

Belief-Based Equilibria in the Repeated Prisoners' Dilemma with Private Monitoring

We analyze repeated prisoners' dilemma games with imperfect private monitoring and construct mixed trigger strategy equilibria. Such strategies have a simple representation, where a player's action only depends upon her belief that her opponent(s) are continuing to cooperate. When monitoring is almost perfect, the symmetric efficient outcome can be approximated in any prisoners' dilemma game, while every individually rational feasible payoff can be approximated in a class of such games. The efficiency result extends when there are more than two players. It requires that monitoring be sufficiently accurate but does not require very low discounting when a public randomization device is available. Journal of Economic Literature Classification Numbers: C73, D82.     

Firm reputation and horizontal integration

We study effects of horizontal integration on firm reputation in an environment where customers observe only imperfect signals about firms' effort/quality choices. Horizontal integration leads to a larger market base for the merged firm, and thus helps reputation building with more effective punishments and better monitoring by eliminating idiosyncratic shocks of individual markets. But it allows the merged firm to deviate only in a subset of markets, which hinders reputation building by making it more difficult for consumers to monitor its quality. We show that these effects give rise to a reputation‐based theory of the optimal firm size and derive its comparative statics.     

Benchmarking therapists: furthering the benchmarking method in its application to clinical practice

Psychotherapy research has been interested in understanding the variability observed among therapists with regard to their treatment effectiveness. An important initial step towards understanding the source of the differences is to reliably identify therapists that are effective. The current paper thus proposes a method for benchmarking therapists against predetermined criteria of effectiveness which could be conducted using any standard statistical package. Basic steps include (a) creating benchmark(s), (b) determining a prior the numerical criteria that constitute as ??effective?? based on the benchmark(s), (c) calculating pre-post effect sizes as an indicator of effectiveness at the case level using statistical adjustments so as to best match clinical (and other) differences among cases, and (d) statistically benchmarking the therapists using a random-effects hierarchical linear modeling. An example is provided that highlights the number of therapists who would be classified as effective based on various numerical criteria and confidence levels.     

Discrete fixed point theorem reconsidered

The aim of this note is to indicate an example that demonstrates the incorrectness of Iimura’s discrete fixed point theorem [Iimura, T., 2003. A discrete fixed point theorem and its applications. Journal of Mathematical Economics 39, 725–742] and to present a corrected statement using the concept of integrally convex sets.     

Folk theorem with communication

This paper proves a new folk theorem for repeated games with private monitoring and communication, extending the idea of delayed communication in Compte [O. Compte, Communication in repeated games with imperfect private monitoring, Econometrica 66 (1998) 597-626] to the case where private signals are correlated.The sufficient condition for the folk theorem is generically satisfied with more than two players, even when other well-known conditions are not. The folk theorem also applies to some two-players repeated games.     

Stable Shareholdings,the Decision Horizon Problem and Earnings Smoothing

Prior studies argue that stable shareholders do not encourage firm managers to manage their earnings to achieve short‐term earnings goals. They also state that firm managers with stable shareholders have an incentive to report smooth earnings to maintain long‐term relationships with such shareholders. We focus on cross‐shareholdings and stable shareholdings owned by financial institutions as stable shareholdings in Japan, and investigate the effect of these ownership structures on earnings management patterns. Specifically, we hypothesize that stable shareholdings are positively associated with the informational components of earnings smoothing. Consistent with our hypothesis, we first find that as stable shareholdings increase, managers are more likely to conduct earnings smoothing that provides useful information to stable shareholders. Further, our additional analysis shows that stable shareholdings reduce incentives for managers to cut discretionary expenditures to meet short‐term earnings benchmarks, implying that stable shareholdings could reduce the possibility of a myopic problem. These results suggest that managers with stable shareholdings tend to report smoother and less volatile earnings, and do not tend to pursue earnings management to attain short‐term earnings targets.     

Dominance of a Class of Stein type Estimators for Optimal Portfolio Weights When the Covariance Matrix is Unknown

For the estimation problem of mean-variance optimal portfolio weights, several previous studies have proposed applying Stein type estimators. However, few studies have addressed this problem analytically. Since the form of the loss function used in this problem is not of the quadratic type commonly used in statistical studies, there have been some difficulties in showing analytically the general dominance results. However, dominance results are given here of a class of Stein type estimators for the mean-variance optimal portfolio weights when the covariance matrix is unknown and is estimated. The class of estimators is broader than the one given in a previous study. The results we have obtained enable us to clarify conditions for some previously proposed estimators in finance to have smaller risks than the estimator which we obtain by plugging in the sample estimates.