The Perceived Stress Scale as a Measure of Stress: Decomposing Score Variance in Longitudinal Behavioral Medicine Studies.

Within two samples differing in age and health status, between-person variance accounted for approximately half of the total variation in PSS scores over time. While within-person variance was observed, the construct assessed by the PSS may substantially reflect a more stable characteristic of how an individual perceives stressful life circumstances than previously appreciated.