Howard, George S.Ralph, Kenneth M.Gulanick, Nancy A.Maxwell, Scott E.Nance, Don W.Gerber, Sterling K.2011-01-312011-01-311979Howard, George S & et al. (1979). Internal invalidity in pretest-posttest self-report evaluations and a re-evaluation of retrospective pretests. Applied Psychological Measurement, 3, 1-23. doi:10.1177/014662167900300101doi:10.1177/014662167900300101https://hdl.handle.net/11299/99490True experimental designs (Designs 4, 5, and 6 of Campbell & Stanley, 1963) are thought to provide internally valid results. This paper describes five studies involving the evaluation of various treatment interventions and identifies a source of internal invalidity when self-report measures are used in a Pretest-Posttest manner. An alternative approach (Retrospective Pretest-Posttest design) to measuring change is suggested, and data comparing its accuracy with the traditional Pretest-Posttest design in measuring treatment effects is presented. Finally, the implications of these findings for evaluation research using self-report instruments and the strengths and limitations of retrospective measures are discussed.enArticle