The diagnostic accuracy of 4 approaches to interpreting neuropsychological
test results an evaluated in 672 cognitively normal and 407 cognitively imp
aired persons using the Mayo Cognitive Factor Scales (G. E. Smith et al., 1
994). The interpretation approaches studied are absolute scores, difference
scores, profile variability, and change scores at 1- to 2-year test-retest
intervals. All dependent measures were "highly significant" when diagnosti
c groups were compared on null hypothesis significance testing analyses. In
contrast, varied accuracy rates were obtained when each measure's ability
to correctly classify individuals was evaluated relative to overall diagnos
tic accuracy. Odds ratios were also highly varied and ranged from less than
or equal to 1.0 (i.e., chance) to 34.9. The clinical usefulness of absolut
e scores and difference scores in data interpretation is supported. Neither
profile variability measures nor measures of change over time were diagnos
tically useful.