Faculté des sciences économiques et sociales

Direct and indirect effects under sample selection and outcome attrition

Huber, Martin ; Solovyeva, Anna

(Working Papers SES ; 496)

This paper considers the evaluation of direct and indirect treatment effects, also known as mediation analysis, when outcomes are only observed for a subpopulation due to sample selection or outcome attrition. For identification, we combine sequential conditional independence assumptions on the assignment of the treatment and the mediator, i.e. the variable through which the indirect effect... Mehr

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    Summary
    This paper considers the evaluation of direct and indirect treatment effects, also known as mediation analysis, when outcomes are only observed for a subpopulation due to sample selection or outcome attrition. For identification, we combine sequential conditional independence assumptions on the assignment of the treatment and the mediator, i.e. the variable through which the indirect effect operates, with either selection on observables/missing at random or instrumental variable assumptions on the outcome attrition process. We derive expressions for the effects of interest that are based on inverse probability weighting by specific treatment, mediator, and/or selection propensity scores. We also provide a brief simulation study and an empirical illustration based on U.S. Project STAR data that assesses the direct effect and indirect effect (via absenteeism) of smaller kindergarten classes on math test scores.