Development and psychometric properties of the Multidimensional Schizotypy Scale: A new measure for assessing positive, negative, and disorganized schizotypy

This article reports on the development of a new self-report questionnaire measure of schizotypy - the Multidimensional Schizotypy Scale (MSS). Schizotypy offers a useful and unifying construct for understanding schizophrenia-spectrum psychopathology. Questionnaire measures have been widely used to assess schizotypy and have greatly informed our understanding of the construct. However, available measures suffer from a number of limitations, including lack of a clear conceptual framework, outdated wording, unclear factor structure, and psychometric shortcomings. The MSS is based on current conceptual models and taps positive, negative, and disorganized dimensions of schizotypy. The derivation sample included 6265 participants sampled from four universities and Amazon Mechanical Turk. A separate sample of 1000 participants from these sources was used to examine the psychometric properties of the final subscales. Scale development employed classical test theory, item response theory, and differential item function methods. The positive schizotypy and negative schizotypy subscales contain 26 items each, and the disorganized schizotypy subscale contains 25 items. The psychometric properties were almost identical in the derivation and validation samples. All three subscales demonstrated good to excellent reliability, high item-scale correlations, and good item and test curve characteristics. The MSS appears to provide a promising measure for assessing schizotypy.