Using the binomial distribution to assess effort: forced-choice testing in neuropsychological settings

The binomial distribution is often, but prematurely, rejected as a tool for assessing effort. This study extended previous research using published clinical and computer-generated pseudo subject data for the Test of Memory Malingering (TOMM). The efficiencies of eight cut points based upon inverse binomial distribution functions were compared with the cut point recommended in the test manual for making correct classifications, and a new statistic, the total number of errors, was also compared with the test manual cut point. Repeated measures, multivariate, and univariate ANOVAs, Bonferroni-corrected post-hoc t-tests, and normal curve density functions were employed to assess the homogeneity of groups within experimental conditions. Based upon these analyses, changes were recommended in the decision rules for the TOMM, and strategies for improving the norms for the TOMM and for neuropsychological assessment instruments, generally, were discussed.