The Performance of Sample Selection Estimators to Control for Attrition Bias.

Sample attrition is a potential source of selection bias in experimental as well as non-experimental programme evaluation. For labour market outcomes such as employment status and earnings, missing data problems caused by attrition can be circumvented by collection of follow-up data from administrative regiters. For most non labour market outcomes however, investigators must rely on participants willingness to cooperate in keeping detailed follow-up records and statistical correction procedures to identify and possibly adjust for attrition bias.