Construct validity of the self-report instrument of perceived stress in the general Costa Rican population of retirement age.

Background: It is known that the effects of stress on the body harm health and mortality outcomes. This phenomenon has been widely studied since its conceptualization. Applying self-report instruments to the general population can help identify degrees of stress and provide evidence on how stress affects social relationships, health, and even mortality. This research aims to explore the internal validity of questions of perceived stress in the general Costa Rican population close to pension or retirement age. Methods: A nationally representative sample of 2743 individuals born between 1945-1955 in Costa Rica completed a series of questions related to perceived stress. Factor analysis, elements of classical test theory, and a Rasch model were used to generate evidence of scale validity. Results: Adequate internal consistency was obtained by factor analysis, with one factor explaining 70% of the variability. The Omega Index value was 0.58. The fit values (INFIT) detected by the Rasch model range between 0.8 and 1.2. Conclusions: the items form a scale that refers to the construct of perceived stress and has sufficient internal consistency.