An Item Response Theory Analysis of the Self- Monitoring Scale

The Self-Monitoring Scale (SMS) was investigated utilizing item response theory (IRT). First, IRT models that constrained each of the subscale items to have equal discrimination were fitted to the three subscales of the SMS (Acting, Extraversion, and Other-Directedness). These models were then contrasted with separate models that allowed the discriminations to be estimated freely. For all three subscales, model comparison tests of significance indicated that the unconstrained models were a better fit. Thus, the items of each subscale are differentially related to their respective underlying construct. Implications and recommendations are offered for future psychometric development and implementation of the SMS.