The relationship between treatment parameters within a latent variable framework

If responses to a treatment vary among people, a variety of parameters can be defined [Heckman, J., Robb, R. 1985, Alternative methods for evaluating the impact of interventions. In: Heckman J., Singer B. (Eds.), Longitudinal Analysis of Labor Market Data. Cambridge University Press, New York, pp. 1 56-245; Heckman, J., 1997, first draft 1995, Instrumental variables: a stud y of implicit behavioral assumptions used in making program evaluations. Jo urnal of Human Resources 32, 441-462]. We show a simple relationship betwee n various treatment parameters when the treatment parameters are defined wi thin a common, latent variable framework. (C) 2000 Elsevier Science S.A. Al l rights reserved.