Rasch analysis of the Perceived Stress Scale: Transformation from an ordinal to a linear measure.

Rasch analysis was conducted to enhance the precision of the widely used 10-item Perceived Stress Scale using two datasets (n = 450 each) randomly selected from samples of the New Zealand general population (n = 1102), New Zealand university students (n = 479) and US university students (n = 396). The best Rasch model fit (χ2(27) = 29.92, p = .36), good person separation reliability (.80) and coverage (98%) of the sample by the scale items were achieved when locally dependent items were combined into subtests. These findings support reliability and internal structural validity of the 10-item Perceived Stress Scale. The instrument precision can be further improved using the ordinal-to-linear conversion tables published here.