Social Interaction Anxiety Scale (SIAS)

Description
The SIAS is a 20 item self report scale designed to measure social interaction anxiety defined as “distress when meeting and talking with other people” (Mattick and Clarke, 1998, p. 457). This tool is helpful in tracking social anxiety symptoms over time, and may be helpful as part of an assessment for social phobia or other anxiety related disorders.

Validity
The SIAS has been compared to other scales that measure social anxiety, including the Social Phobia and Anxiety Inventory (SPAI). Peters (2000) found that they were highly significantly correlated (r = 0.86, P<0.001) suggesting the scales tap similar constructs. Clinician-rated severity of social phobia has also been found to be moderately related to SIAS scores (Brown, et al., 1997). The SIAS has been found to have strong sensitivity to treatment change (Cox, et al., 1998). However, it does not distinguish between social phobia and other anxiety disorders (Peters, 2000). Accordingly, it is recommended that the SIAS should be used as a tool to track treatment progress, and should not be heavily relied upon for differential diagnosis. Interpretation
Peters (2000) defined the cut off score as 36 for probable social phobia. At this score the scale has a sensitivity of 0.93 and specificity of 0.60, with a positive predictive value (PPV) of 0.84 and a negative predictive value (NPV) of 0.78. The average score among people with previously diagnosed social phobia (n=74) was 55.24 (SD=1.97) while for other anxiety disorders (n=34) the mean was 29.46 (SD=29).
Results consist of three scores: the raw score, the raw score converted into a percentile using a social phobia sample, and a percentile in an anxiety sample. A percentile of 50 for the social phobia sample indicates that the client has an average level of symptoms compared to others with social phobia, while percentiles above 50 represent more severe symptoms. There is no standardisation using a normal sample.

Developer
Mattick, R. P., & Clarke, J. C. (1998). Development and validation of measures of social phobia scrutiny fear and social interaction anxiety1. Behaviour Research and Therapy, 36(4),
455-470.