Assessment of differential item functioning in the Perceived Stress Scale-10.

DiVerential item functioning is the degree to which items that comprise a measurement scale are systematically related to various exogenous variables (for example, sex, race, etc) after conditioning on the latent variable of interest, which is often represented by the total scale score. When an item functions diVerentially with respect to an exogenous variable and the source of this diVerential functioning is irrelevant to the construct measured the item is termed “biased.” Description of item functioning, a relatively modern psychometric development, is tantamount to providing evidence for, or against, construct validity, and is therefore of imminent importance to the use of measurement scales in epidemiological research. The 10-item Perceived Stress Scale (PSS10) is a popular Likert-type rating scale developed to quantify the psychological construct “perceived stress.” Herein, we present the first results of diVerential item functioning in the PSS-10.