Psychometric function of the "neutral" response option in clinical personality scales
McFadden, Lisa S.
Krug, Samuel E.
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McFadden, L. S., Krug, S. E. (1984). Psychometric Function of the "Neutral" Response Option in Clinical Personality Scales. Multivariate Experimental Clinical Research, 7(1), 25-33.
Two of the most widely-used diagnostic personality inventories, the Minnesota Multiphasic Personality Inventory (MMPI) and the Clinical Analysis Questionnaire (CAQ), differ importantly in their scoring of the "neutral" or "uncertain" response option. The MMPI aggregates all such responses into a separate validity index while the CAQ incorporates them into substantive scale scores. An empirical analysis was made of the impact on reliability and validity when the neutral component is included in or excluded from substantive scale scores. Scores on the 12 pathological scales of the CAQ were partitioned into one part due to endorsement of the keyed (i.e., "true" or "false") alternative and a part due to endorsement of the neutral (i.e., "uncertain") response choice. With respect to discriminating between 150 psychiatrically diagnosed and 150 normal adults, regression analyses showed that addition of the neutral component to the keyed component significantly improved the validity of the scales 75% of the time, with the average gain of 7% in variance explained. Improvement was greeted for the most severe diagnostic category. Alpha coefficients computed for each scoring method further revealed that including the neutral in the total score resulted in an average improvement of 10% in scale reliability. Despite a tendency on the part of many to think of all structured personality inventories as homogeneous class of measurement techniques, the reality is that self-report instruments are published in a wide variety of formats. In some cases forced-choice designs simultaneously present two or more items to the examinee. More often, examinees are asked to respond separately to each item in the inventory.