Development of a short form Social Interaction Anxiety (SIAS) and Social Phobia Scale (SPS) using nonparametric item response theory: the SIAS-6 and the SPS-6.

Shortened forms of the Social Interaction Anxiety Scale (SIAS) and the Social Phobia Scale (SPS) were developed using nonparametric item response theory methods. Using data from socially phobic participants enrolled in 5 treatment trials (N = 456), 2 six-item scales (the SIAS-6 and the SPS-6) were developed. The validity of the scores on the SIAS-6 and the SPS-6 was then tested using traditional methods for their convergent validity in an independent clinical sample and a student sample, as well as for their sensitivity to change and diagnostic sensitivity in the clinical sample. The scores on the SIAS-6 and the SPS-6 correlated as well as the scores on the original SIAS and SPS, with scores on measures of related constructs, discriminated well between those with and without a diagnosis of social phobia, providing cutoffs for diagnosis and were as sensitive to measuring change associated with treatment as were the SIAS and SPS. Together, the SIAS-6 and the SPS-6 appear to be an efficient method of measuring symptoms of social phobia and provide a brief screening tool.