Tests based on generalized-method-of-moments estimators often have true levels that differ greatly from their nominal levels when asymptotic critical values are used. This paper gives conditions under which the bootstrap provides asymptotic refinements to the critical values of t tests and the test of overidentifying restrictions. Particular attention is given to the case of dependent data. It is shown that, with such data, the bootstrap must sample blocks of data and that the formulae for the bootstrap versions of the test statistics differ from the formulae that apply with the original data. Copyright 1996 by The Econometric Society.

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We analyze the timing, pace, and efficiency of ongoing job reallocation that results from product and process innovation. There are strong reasons why an efficient economy ought to concentrate both job creation and destruction during recessions, when the opportunity cost of reallocation is lowest. Incomplete contracting between labor and capital can disrupt this synchronized pattern and decouple creation and destruction. Transactional difficulties also lead to technological “sclerosis,” characterized by excessively slow renovation. Government incentives to production may alleviate high unemployment but exacerbate sclerosis. In contrast, creation incentives increase the pace of reallocation. An optimal combination of both policies restores economic efficiency.

We present a finite system of polynomial inequalities in unobservable variables and market data that observations on market prices, individual incomes and aggregate endowments must satisfy to be consistent with the equilibrium behavior of some pure trade economy. Quantifier elimination is used to derive testable propositions on finite data sets for the pure trade model.