This Digest, intended as an instructional aid for beginning research students and a refresher for researchers in the field, identifies key factors that play a critical role in determining the credibility that should be given to a specific research study. The needs for empirical research, randomization and control, and significance testing are discussed, and seven review criteria are proposed. These criteria are: (1) randomization; (2) control; (3) reliability; (4) validity; (5) implementation of treatment variable; (6) analysis issues; and (7) interpretation issues. (SLD)