We test the null hypothesis that two parameters (μ1,μ2) have the same sign, assuming that (asymptotically) normal estimators (ˆμ1, ˆμ2) are available. Examples of this problem include the analysis of heterogeneous treatment effects, causal interpretation of reduced-form...

This paper exploits a new source of variation in Head Start funding to identify the program's effects on health and schooling. In 1965 the Office of Economic Opportunity (OEO) provided technical assistance to the 300 poorest counties to develop Head Start proposals. The result was a large and...

This paper exploits a new source of variation in Head Start funding to identify the program s effects on health and schooling. In 1965 the Office of Economic Opportunity (OEO) provided technical assistance to the 300 poorest counties in the U.S. to develop Head Start funding proposals. The...

Microeconometrics researchers have increasingly realized the essential need to account for any within-group dependence in estimating standard errors of regression parameter estimates. The typical preferred solution is to calculate cluster-robust or sandwich standard errors that permit quite...

In this paper we survey methods to control for regression model error that is correlated within groups or clusters, but is uncorrelated across groups or clusters. Then failure to control for the clustering can lead to understatement of standard errors and overstatement of statistical...

In this paper we survey methods to control for regression model error that is correlated within groups or clusters, but is uncorrelated across groups or clusters. Then failure to control for the clustering can lead to understatement of standard errors and overstatement of statistical...

In this paper we propose a variance estimator for the OLS estimator as well as for nonlinear estimators such as logit, probit and GMM. This variance estimator enables cluster-robust inference when there is two-way or multi-way clustering that is non-nested. The variance estimator extends the...

In recent years, there has been an astonishing proliferation of empirical work on child labor. An Econlit search of keywords child labor reveals a total of 6 peer reviewed journal articles between 1980 and 1990, 65 between 1990 and 2000, and 143 in the first five years of the present decade. The...

Do the short and medium term adjustment costs associated with trade liberalization influence schooling and child labor decisions? We examine this question in the context of India's 1991 tariff reforms. Overall, in the 1990s, rural India experienced a dramatic increase in schooling and decline in...

Why do young children migrate without a parent? We consider the economic components of the answer to this question by examining the correlates of out-migration for children under 15 whose mother's reside in Bihar and Uttar Pradesh, India. 1 million children appear to have migrated away from home...