A Quasi-Experimental Design for the Assessment of Posttest Sensitization

Abstract

Researchers have long been aware that "pretest sensitization" is a potential threat to the external validity of experimental studies. Only recently, however, has it been suggested that "posttest sensitization" might also limit the generalizability of results. This latter phenomenon would exist if the administration of a posttest caused the treatment's impact to become more (or less) pronounced. Under this condition, the treatment would work differently for Ss in the researcher's sample than for other individuals who might later receive only the treatment without the accompanying posttest. To be scientifically useful, it is imperative that the hypothesis of posttest sensitization be capable of empirical verification. A quasi-experimental design is proposed for this purpose.