Estimation of Time Dependent Parameters in Linear Models Using Cross Sections, Panels, or Both (Revised)

摘要

In the note the authors consider the estimation of time dependent parameters in linear models from panel data, cross sections or both. They determine the fraction of individuals that should be reinterviewed each period in order to minimize the variance of the most efficient estimator of linear combinations of the parameters. Moreover, the authors derive simple sufficient conditions for the optimal fraction to be zero or one respectively.