Section SixExperimental Designs
Source: Adapted from Donald T. Campbell and Julian C. Stanley. Experimental and
Quasi-Experimental Designs for Research. Boston: Houghton Mifflin Company, 1966; and
Wayne F. Cascio. Applied Psychology in Personnel Management, 4th ed. Upper Saddle
River, NJ: Prentice Hall, 1991.
The first is the pretest–posttest control group design,
which includes both experimental and control groups.
Assignment of participants to these groups is based on random
selection in order to control for such contaminants as
differences in ability, experience, and the like. Prior to the com-
mencement of training, both groups are pretested on the
effectiveness criteria (e.g., knowledge of concepts, skill levels).
The experimental group then receives the training while the
control group does not. After completion of the training, and
any appropriate time lags for behaviors to be manifested, both
groups are posttested. The statistical approach for assessing
the significance of results involves the computation of gain