Abstract
This article addresses certain poor practices commonly seen in the applied health economics literature regarding the use of the Heckit and the two-part model. First, many articles invoke the Heckit to solve a supposed selection problem associated with masses of zero values in continuous variables, despite the fact that it has been shown elsewhere that no such selection problem exists when modeling observed actual, as opposed to latent potential, outcomes. Second, many applications incorrectly formulate the marginal effect tests in the Heckit and two-part model, thus undermining central conclusions. Finally, many researchers use a t-test of the inverse Mills coefficient to choose between the Heckit and two-part models despite its poor performace; we propose instead an adapted empirical mean square error test.
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Ai, C. and Norton, E.C., “Standard errors for the retransformation problem with heteroscedasticity,” Journal of Health Economics 19(5), 697–718, 2000.
Angrist, J.D., “Estimations of limited dependent variable models with dummy endogenous regressors: Simple strategies for empirical practice,” Journal of Business and Economic Statistics 19, 2–16, 2001. 18 DOW AND NORTON
Duan, N., Manning, W.G., Morris, C.N., and Newhouse, J.P., “A comparison of alternative models for the demand for medical care,” Journal of Business and Economic Statistics 1, 115–126, 1983.
Duan, N., Manning, W.G., Morris, C.N., and Newhouse, J.P., “Choosing between the sample-selection model and the multi-part model,” Journal of Business and Economic Statistics 2, 283–289, 1984.
Gilleskie, D.B. and Mroz, T.A., “Estimating the effects of covariates on health expenditures,” Working paper, Department of Economics, University of North Carolina at Chapel Hill, 2000.
Greene, W.H., Econometric analysis, 4th edn., Prentice Hall, Inc., Upper Saddle River, 2000.
Hay, J.W., Leu, R., and Fohrer, P., “Ordinary least squares and sample-selection models of health-care demand,” Journal of Business and Economic Statistics 5, 499–506, 1987.
Hay, J.W. and Olsen, R.J., “Let them eat cake: A note on comparing alternative models of the demand for health care,” Journal of Business and Economic Statistics 2, 279–282, 1984.
Heckman, J.J., “What has been learned about labor supply in the past twenty years?” American Economic Review 83(2), 116–121, 1993.
Jones, A.M., Health Econometrics, in Handbook of Health Economics (A.J. Culyer and J.P. Newhouse, eds.), North Holland, Amsterdam, 265–344, 2000.
Lee, L.-F., “Some approaches to the correction of selectivity bias,”Review of Economic Studies 49, 355–372, 1982.
Lee, L.-F., “Generalized econometric models with selectivity,”Econometrica 51, 507–512, 1983.
Leung, S.F. and Yu, S., “On the choice between sample selection and two-part models,”Journal of Econometrics 72, 197–229, 1996.
Manning, W.G., “The logged dependent variable, heteroscedasticity, and the retransformation problem,” Journal of Health Economics 17, 283–296, 1998.
Manning, W.G., Duan, N., and Rogers, W.H., “Monte Carlo evidence on the choice between sample selection and two-part models,” Journal of Econometrics 35, 59–82, 1987.
Mullahy, J., “Much ado about two: Reconsidering retransformation and the two-part model in health econometrics,” Journal of Health Economics 17, 247–282, 1998.
Mullahy, J., “Estimations of limited dependent variable models with dummy endogenous regressors: Simple strategies for empirical practice: Comment,” Journal of Business & Economic Statistics 19, 23–25, 2001.
Salas, C. and Raftery, J.P., “Econometric issues in testing the age neutrality of health care expenditure,” Health Economics 10, 669–671, 2001.
Toro-Vizcarrondo, C. and Wallace, T.D., “A test of the Mean Square Error criterion for restrictions in linear regression,” Journal of the American Statistical Association 558–72, 1968.
van de Ven, W.P. and van Praag, B.M., “Risk aversion of deductibles in private health insurance: Application of an adjusted Tobit model to family health care expenditures,” in Health, Economics and Health Economics (J. van der Gaag and M. Perlman, eds.), North Holland, Amsterdam, 125–148, 1981.
Wooldridge, J.M., Econometric analysis of cross section and panel data, MIT Press, Cambridge, MA, 2002.
Zweifel, P., Felder, S, and Meiers, M., “Ageing of population and health care expenditure: A red herring?” Health Economics 8, 485–496, 1999.
Zweifel, P., Felder, S., and Meier, M., “Reply to: Econometric issues in testing the age neutrality of health care expenditure,” Health Economics 10, 673–674, 2001.
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Dow, W.H., Norton, E.C. Choosing Between and Interpreting the Heckit and Two-Part Models for Corner Solutions. Health Services & Outcomes Research Methodology 4, 5–18 (2003). https://doi.org/10.1023/A:1025827426320
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DOI: https://doi.org/10.1023/A:1025827426320