Differential Item Functioning of the Full and Brief Wisconsin Schizotypy Scales in Asian, White, Hispanic, and Multiethnic Samples and Between Sexes.

The Wisconsin Schizotypy Scales, including their brief versions, are among the most commonly used self-report measures of schizotypy. Although they have been used extensively in many ethnic groups, few studies have examined their differential item functioning (DIF) across groups. The current study included 1,056 Asian, 408 White, 476 Multiethnic, and 372 Hispanic undergraduates. Unidimensional models of the brief Magical Ideation Scale and Perceptual Aberration Scales fit the data well. For both scales, global tests of measurement invariance provided mixed evidence, but few of the items displayed DIF across ethnicities or between sexes within a multiple indicator multiple causes model. For the full versions of the scales and the brief Revised Social Anhedonia Scale, multiple indicator multiple causes models within an exploratory structural equation modeling framework found that few of the items had DIF. These findings suggest that some of the items may have different psychometric properties across groups, but most items do not.