Problems of sample selection arise in the analysis of both experimental and non-experimental data. In clinical trials to evaluate the impact of an intervention on health and mortality, treatment assignment is typically nonrandom in a sample of survivors even if the original assignment is random....

The average effect of intervention or treatment is a parameter of interest in both epidemiology and econometrics. A key difference between applications in the two fields is that epidemiologic research is more likely to involve qualitative outcomes and nonlinear models. An example is the recent...

A combination of voluntary enlistment, armed forces eligibility criteria, and the failure of draftees to avoid conscription jointly determined the racial composition of the Vietnam-era armed forces. Administrative data show that men with draft lottery numbers that put them at high risk of...

The majority of armed forces veterans make use of the subsidized training and educational benefits provided by the Department of Veterans Affairs. The effect of veterans benefits on educational attainment am civilian earnings is estimated here using the Census Bureau's 1987 Survey of Veterans....

Economists have long debated over what labor supply has to do with fluctuations in hours worked. This paper uses a time series of cross-sections from the 1964-88 Current Population Surveys to study whether microeconomic intertemporal substitution models can explain time series fluctuations in...

Instrumental Variables (IV) methods identify internally valid causal effects for individuals whose treatment status is manipulable by the instrument at hand. Inference for other populations requires some sort of homogeneity assumption. This paper outlines a theoretical framework that nests all...