Unavoidable sample size issues beset psychological research that involves scarce populations or costly laboratory procedures. When incorporating longitudinal designs these samples are further reduced by traditional modeling techniques, which perform listwise deletion for any instance of missing data. Moreover, these techniques are limited in their…

In many arenas, the demand for data has outstripped the availability of good data and has increased the tendency to grab for whatever numbers are being circulated in the literature. As a result, when someone says: "This is the best data available," it is essential to remember that "best" does not always mean good. This caution is particularly…