Motivated by findings in the literature suggesting that error attributed to measures used in generating retrospective reports are excessive, this study explores error attributed to methods that individuals use for calculating change retrospectively. Preliminary findings indicate that method variation is present which, in turn, affects the reported change scores (i.e., the scores varied as a function of the calculation method used). These findings suggest that the accuracy and
comparability of retrospective reporting might be improved if one controls for inter-individual calculation method variation. A brief discussion of the implications of the results along with suggestions for future research is provided.