Psychometric properties of the Multidimensional Schizotypy Scale and Multidimensional Schizotypy Scale–Brief: Item and scale test–retest reliability and concordance of original and brief forms

We conducted 2 studies examining the psychometric properties of the Multidimensional Schizotypy Scale (MSS) and the Multidimensional Schizotypy Scale–Brief (MSS–B). These studies offered the first examination of the scales’ test–retest reliability (dependability), impact of testing interval on test–retest reliability, and concordance of the 2 versions. The MSS and MSS–B contain positive, negative, and disorganized schizotypy subscales that reflect current models of schizotypy. In Study 1, MTurk participants (n?=?245) completed the scales at 2 assessments across a 7-week time interval. Test–retest reliabilities (intraclass correlations) ranged from .84 to .90 for the MSS subscales and from .77 to .85 for the MSS–B subscales, and were unaffected by the interval length between administrations. The association between the same subscales of the MSS and MSS–B across the 2 assessments ranged from .79 to .87, indicating good correspondence between the MSS and MSS–B. Scores on the MSS–B subscales in Study 1 were derived from the full-length MSS. Therefore, we replicated the findings using the actual MSS–B subscales in Study 2 in 3 samples (total n?=?339). The results indicated that the MSS and MSS–B have good internal consistency and test–retest reliabilities (dependability), and that there is high concordance between the full-length and brief versions