Bubbles as payoffs at infinity

Summary We define rational bubbles to be securities with payoffs occurring in the infinitely distant future and investigate the behavior of bubbles values. We extend our analysis to a setting of uncertainty. In an infinite horizon arbitrage-free model of asset prices, we interpret the money market account as the value of a particular bubble; a similar interpretation holds for other assets related to the state-price deflator and to payoffs on bonds maturing in the distant future. We present three applications of this characterization of bubbles.This paper was circulated under the title Stochastic bubbles in Markov economies. We acknowledge with gratitude numerous conversations with Mark Fisher, the editorial advice of David Levine and the useful comments of anonymous referees. This paper should not be interpreted as reflecting the views of the Board of Governors of the Federal Reserve System or its staff.     

Network potentials

A network payoff function assigns a utility to all participants within a social network. In this paper we investigate network payoff functions that admit an exact network potential or an ordinal network potential. We also investigate exact and ordinal potentials of Myerson’s non-cooperative network formation game based on consent in link formation. We show that the admittance of certain of these network and game-theoretic potentials implies the existence of pairwise stable networks and the convergence of network formation processes. Our main results extend and strengthen the current insights in the literature on game theoretic approaches to social network formation. We thank Matt Jackson and Sudipta Sarangi for extensive discussions on the subject of this paper. Part of this research was done while S. Chakrabarti was at Bonn on a post-doctoral research fellowship. We thank the Department of Economics at the University of Bonn for their hospitality and financial support. Part of this research was done at the Center for Economic Research at Tilburg University, Tilburg, the Netherlands. R. P. Gilles financially supported from the Netherlands Organization for Scientific Research (NWO), grant # 46-550, is gratefully acknowledged.     

Interpretable Machine Learning Using Partial Linear Models*

Despite their high predictive performance, random forest and gradient boosting are often considered as black boxes which has raised concerns from practitioners and regulators. As an alternative, we suggest using partial linear models that are inherently interpretable. Specifically, we propose to combine parametric and non-parametric functions to accurately capture linearities and non-linearities prevailing between dependent and explanatory variables, and a variable selection procedure to control for overfitting issues. Estimation relies on a two-step procedure building upon the double residual method. We illustrate the predictive performance and interpretability of our approach on a regression problem.     

Intergenerational Wealth Mobility in France, 19th and 20th Century

This paper examines intergenerational wealth mobility between fathers and children in France between 1848 and 1960. Considering wealth mobility in the long run requires taking into account not only positional mobility (that is, how families move within a given distribution of wealth), but also structural mobility induced by changes in the distribution of wealth. Such changes are related to two structural phenomena: in the nineteenth century, the rising number of individuals leaving no estate at death and, after World War I, the decline in the number of the very rich who could live off their wealth. The paper studies the movements between these groups and estimates the intergenerational elasticity of wealth, taking into account the persistence at the bottom and at the top.     

MARKET ECONOMIES WITH AN ENDOGENOUS SOCIAL DIVISION OF LABOR

I consider a general equilibrium model of a competitive market economy in which production is conducted through an endogenous social division of labor. I represent economic decision makers as “consumer–producers,” who consume as well as produce commodities. In this approach, the emergence of a nontrivial social division of labor is guided by Increasing Returns to Specialization (IRSpec) in production. Under IRSpec, I show existence of competitive equilibria, the two fundamental theorems of welfare economics, and characterize these equilibria. Markets equilibrate through the adjustment of the social division of labor; the production technologies completely determine the equilibrium prices.     

Contracting Out in Japanese Local Government: Are Unions Making a Difference?

Using 1997 data for Japanese cities, we examine the relationship between union density and outsourcing in local government. We also test the hypothesis that cities where employees are represented by the more radical of the two local civil service unions will have less outsourcing than cities where the less critically oriented union dominates. The results of the analysis support the central hypothesis that union density is negatively correlated with outsourcing, but they do not support the second hypothesis.     

Promoting innovation and competition with patent policy

Recently the role of institutions on growth, and especially the influence of Intellectual Property Rights, has been integrated into the Schumpeterian Growth Framework. In this contribution, we highlight the possibility using one patent’s characteristic, the patent height, as an instrument for promoting innovation and growth. We introduce this possibility into the Segerstrom (Am Econ Rev 80:1290–1310, 1998)/Li (Am Econ Rev 93:1009–1018, 2003) quality ladders model of growth. The Li (Am Econ Rev 93: 1009–1018, 2003) generalized model overturns Segerstrom (Am Econ Rev 80:1290–1310, 1998) policy implication in terms of the size of innovations having to be taxed or subsidized by relaxing a crucial assumption on the value of the elasticity of substitution between goods. In this paper, we point out the fact that the innovation size requirement has to be considered as a policy instrument, so that it appears extremely important to consider the case when the innovation size has been made endogenous. A patent policy using the novelty requirement as an instrument for innovation policy enables implementation of the social optimum. The consequences of this policy for market structure and economic growth are then discussed. When the level of the patent novelty requirement is initially high, a patent policy that weakens the patent height can reinforce competition and promote innovation.