ABSTRACT
Precious few have tried to conduct long-term studies aimed at answering such big questions. Longitudinal research is difficult and expensive. It is difficult to keep track of people and collect data from them after a considerable passage of time; to define trenchant criteria and develop appropriate measures; to distinguish effects of the treatment from those of other events and circumstances (" ... time and chance happeneth to them all"; Ecclesiates, 9:11); and (a crucial question) to determine at what point in careers to appraise success and satisfaction.
