The use of ability testing for job selection has become widespread in the Federal Government and in the U.S. Employment Service, which assists private sector employers. The justification for the practice is based largely on research findings claiming a high level of validity for such tests in predicting job performance. More recently, such claims…

This research is, in part, a study of a method of differentiating between two different types of retardation (the exogenous or brain injured and the endogenous or non-brain injured). However, this paper is also an example of the evaluation of a research problem, for it incorporates data and information from three different studies, each of which…