Self-Report Evaluations of Training Effectiveness: Measuring Alpha, Beta, and Gamma Change

Abstract

Although self-report measures are often used as criteria in treatment interventions, the contaminating effects of response-shift bias associated with these scales are less frequently evaluated. G.S. Howard and his co-workers (Howard, Schmeck, & Bray, 1979) have suggested that response-shift bias can be measured and controlled by gathering and analysing retrospective Pretest scores in addition to the conventional Pretest and Posttest information normally obtained in change studies. In this study these measures were gathered from participants in an assertiveness training programme. The aim was to assess the extent to which subjects had recalibrated the scales of measurement (i.e., beta change) and reconceptualized the construct of assertiveness (i.e., gamma change) from Pretest to Posttest. These two forms of response-shift bias were recorded for a number of trainees. Apart from finding that the usual Pretest/Posttest design offers a more conservative estimate of treatment effects than the approach using retrospective scores, the results showed that the latter approach has particular utility in diagnosing the nature and extent of change experienced by individuals in treatment interventions.