| Abstract: | "In analyzing the extraneous variables which experimental designs for social settings seek to control, seven categories have been distinguished: history, maturation, testing, instrument decay, regression, selection, and mortality. In general, the simple or main effects of these variables jeopardize the internal validity of the experiment and are adequately controlled in standard experimental designs. The interactive effects of these variables and of experimental arrangements affect the external validity or generalizability of experimental results. Standard experimental designs vary in their susceptibility to these interactive effects." 37 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
