We derive the efficiency loss from using grouped data to estimate coefficients of variables that vary across groups but not individuals within a group (e.g., state unemployment rates) when micro data are unavailable on the dependent variable. We present an empirical example of our theoretical...

Background: Although various prescription drugs may be equally effective in promoting sleep, some may lead to substantial impairment in psychomotor functioning and an increased risk of motor vehicle accidents. Objective: To develop a general model to evaluate the potential effects of sleep...