The Common Item In Measurement: Effects On Structure

Procedures for analyzing common item effects on the inference of personality structure were reviewed and a study using smallest space analysis of the CPI reported. Solutions to three matrices -- intercorrelation matrix of the original CPI scales, of reduced scales (with common items removed), and of the number of common items -- were compared visually, and by interpoint distance correlations and configurational similarity analyses. Marked similarity among the original structure, the item-overlap-free structure and the built-in structure was observed. It was concluded that common items magnify an intrinsic structure already existing among scales and that the common-item problem is not likely a serious on in personality measurement.