The score function is associated with some optimality features in statistical inference. This review article looks on the central role of the score in testing and estimation. The maximization of the power in testing and the quest for efficiency in estimation lead to score as a guiding principle....

Existing studies of household stock trading using administrative data offer conflicting results: Discount brokerage accounts exhibit excessive trading, while retirement accounts show inactivity. This paper uses population-wide data from PSID and SCF to examine the overall extent of household...