SangMok Lee

The Money Pump as a Measure of Revealed Preference Violations

We introduce a measure of the severity of violations of the revealed preference axioms, the money pump index (MPI). The MPI is the amount of money one can extract from a consumer who violates the axioms. It is also a statistical test for the hypothesis that a consumer is rational when behavior is observed with error. We present an application using a panel data set of food expenditures. The data exhibit many violations of the axioms. Mostly, the MPI for these violations is small. The MPI indicates that the hypothesis of consumer rationality cannot be rejected.

Aggregate matchings

This paper characterizes the testable implications of stability for aggregate matchings. We consider data on matchings where individuals are aggregated, based on their observable characteristics, into types, and we know how many agents of each type match. We derive stability conditions for an aggregate matching, and, based on these, provide a simple necessary and sufficient condition for an observed aggregate matching to be rationalizable (i.e. such that preferences can be found so that the observed aggregate matching is stable). Subsequently, we derive moment inequalities based on the stability conditions, and provide an empirical illustration using the cross-sectional marriage distributions across the US states.

On the Efficiency of Stable Matchings in Large Markets

Stability is often the goal for clearinghouses in matching markets, such as those matching residents to hospitals, students to schools, etc. Stable outcomes absent transfers need not be utilitarian efficient, suggesting the potential value of transfers. We study the wedge between stability and efficiency in large one-to-one matching markets. We show stable matchings are efficient asymptotically for a large class of preferences. In these environments, stability remains an appealing objective even on efficiency grounds, and monetary transfers are not necessary for efficiency purposes. Nonetheless, for severely imbalanced markets, when preferences entail sufficient idiosyncrasies, stable outcomes may be inefficient even asymptotically.

PARTIAL IDENTIFICATION IN TWO-SIDED MATCHING MODELS

We propose a methodology for estimating preference parameters in matching models. Our estimator applies to repeated observations of matchings among a fixed group of individuals. Our estimator is based on the stability conditions in matching models; we consider both transferable (TU) and nontransferable utility (NTU) models. In both cases, the stability conditions yield moment inequalities which can be taken to the data. The preference parameters are partially identified. We consider simple illustrative examples, and also an empirical application to aggregate marriage markets.