Diagnostic validity of the Minnesota percepto-diagnostic test for adults : a meta-analysis

A potential psychometric resource for use in serving the special needs of adult learners is the Minnesota Percepto-Diagnostic Test (MPD). However, claims for the MPD's diagnostic validity were mixed. The objective of the study, therefore, was to empirically examine the research literature from 1963 to the present to determine if MPD data had demonstrated the instrument's capacity to differentiate: (1) organic from personality disturbed samples; (2) organic from normal samples; and (3) personality disturbed from normal samples. Evidence of diagnostic validity required the data to demonstrate that design rotation scores for organic samples exceeded those of personality disturbed samples (contrast 1) and normal samples (contrast 2), and that the scores of personality disturbed samples, in turn, exceeded those of normal samples (contrast 3). With alpha set at .05, meta-analysis results supported claims for diagnostic validity. The result for each contrast was significant, and the null hypothesis that true effect size equaled zero could be rejected at the .95 level of confidence. In conclusion, results and application issues were discussed, and future research efforts were recommended.