Presenting and analyzing results in aging research: a methodological note.

Salthouse (1991) suggested two methods of presenting and analyzing the data of studies in which patterns of performance for young and old participants in different tasks are compared. The first method presents the original scores in terms of the standard deviations of the distribution of the young adults group, and in the second method, the reference distribution is performance of each age group in a control or baseline condition. The authors question the arbitrariness of the baseline chosen in both methods, which might lead to misleading results, and reanalyze the results of 2 studies and show that alternative, equally legitimate methods, using different baseline conditions, yield different results. This raises a question regarding the suitability of a derived-scores methodology in presenting and analyzing summary results.