Monte Carlo evidence on the choice between sample selection and two-part models

https://doi.org/10.1016/0304-4076(87)90081-9Get rights and content

Abstract

This Monte Carlo study examines the relative performance of sample selection and two-part models for data with a cluster at zero. The data are drawn from a bivariate normal distribution with a positive correlation. The alternative estimators are examined in terms of means squared error, mean bias and pointwise bias. The sample selection estimators include LIML and FIML. The two-part estimators include a naive (the true specification, omitting the correlation coefficient) and a data-analytic (testimator) variant.

In the absence of exclusion restrictions, the two-part models are no worse, and often appreciably better than selection models in terms of mean behavior, but can behave poorly for extreme values of the independent variable. LIML had the worst performance of all four models. Empirically, selection effects are difficult to distinguish from a non-linear (e.g., quadratic) response. With exclusion restrictions, simple selection models were significantly better behaved than a naive two-part model over subranges of the data, but were negligibly better than the data-analytic version.

References (29)

  • A.S. Goldberger

    Abnormal selection bias

  • J.W. Hay et al.

    Let them eat cake: A note on comparing alternative models of the demand for health care

    Journal of Business and Economic Statistics

    (1984)
  • J. Heckman

    Shadow prices, market wages, and labor supply

    Econometrica

    (1974)
  • J. Heckman

    The common structure of statistical models of truncation, sample selection, and limited dependent variables, and sample estimator for such models

    Annals of Economic and Social Measurement

    (1976)
  • Cited by (254)

    View all citing articles on Scopus

    We would like to thank Scott Cardell, Emmett Keeler, Lee Lillard, Carl Morris, Joe Newhouse, John Rolph, and Wynard van de Ven for their comments and support. Careful reviews by two anonymous referees have helped to markedly improve this paper. Bob Young and Karl Schutz provided programming support.

    View full text