Picturing repeated measures: Comments on Loftus, Morrison, and others

Loftus's (1993b, 1995) recommendation that investigators routinely include plots of appropriate means along with 95%confidence intervals or some other indication of variability has considerable merit, yet we agree with Morrison and Weaver (1995) that such plots can supplement but not supplant the usual reporting of analysis of variance results. Providing them may be easier than Loftus and Masson (1994) indicated, especially when error bars are understood as supplemental descriptive devices. We suggest a general, unified approach that applies to the explication of both betweenand within-subjects effects. Variability is estimated separately for each group of scores identified as different by analysis because this serves description better. Raw scores are used for between-subjects effects, scores adjusted for between-subjects variability for within-subjects effects. Allcomputations and figures are easily effected using common spreadsheet programs.