Causal Inference and Nonrandom Samples

Wainer (1989) confuses two conceptually distinct problems in his discussion of the problems of statistical adjustment. Clarity would be served by distinguishing these problems. The first and stated main problem of the paper is that of making "causal inferences" about the impacts of "treatments" or "interventions" when persons self-select or are selected into treatment categories. The second problem is that of recovering population distributions from nonrandom samples. The paper is likely to confuse most readers because it switches from the first problem to the second problem in the "Modeling Nonresponse" section. A solution to the second problem in no way guarantees a solution to the first.

[1]  James J. Heckman,et al.  Longitudinal Analysis of Labor Market Data , 1985 .

[2]  Stephan Morgenthaler,et al.  Choice-based samples: A non-parametric approach , 1986 .

[3]  S. Cosslett,et al.  Maximum likelihood estimator for choice-based samples , 1981 .

[4]  D. Rubin,et al.  The central role of the propensity score in observational studies for causal effects , 1983 .

[5]  R. A. Fisher,et al.  Design of Experiments , 1936 .

[6]  Donald B. Rubin,et al.  Selection Modeling Versus Mixture Modeling with Nonignorable Nonresponse , 1986 .

[7]  David R. Cox.  Planning of Experiments , 1958 .

[8]  J. Heckman.  Sample selection bias as a specification error , 1979 .

[9]  Howard Wainer,et al.  Drawing inferences from self-selected samples , 1986 .

[10]  A. Gallant,et al.  Semi-nonparametric Maximum Likelihood Estimation , 1987 .

[11]  Howard Wainer,et al.  Eelworms, Bullet Holes, and Geraldine Ferraro: Some Problems With Statistical Adjustment and Some Solutions , 1989 .

[12]  James J. Heckman,et al.  Choosing Among Alternative Nonexperimental Methods for Estimating the Impact of Social Programs: the Case of Manpower Training , 1989 .

[13]  M. Woodroofe.  Estimating a Distribution Function with Truncated Data , 1985 .

[14]  Charles F. Manski,et al.  Alternative Estimators and Sample Designs for Discrete Choice Analysis , 1981 .

[15]  J. Powell,et al.  Semiparametric Estimation Of Bivariate Latent Variable Models , 1987 .

[16]  Chris Robinson,et al.  The Joint Determination of Union Status and Union Wage Effects: Some Tests of Alternative Models , 1989, Journal of Political Economy.

[17]  O. Ashenfelter,et al.  Estimating the Effect of Training Programs on Earnings , 1976 .

[18]  James J. Heckman,et al.  Alternative methods for solving the problem of selection bias in evaluating the impact of treatments , 1986 .

[19]  James J. Heckman,et al.  Do We Need Experimental Data To Evaluate the Impact of Manpower Training On Earnings? , 1987 .

[20]  Y. Vardi.  Empirical Distributions in Selection Bias Models , 1985 .

[21]  A. Roy.  Some thoughts on the distribution of earnings , 1951 .