Assessing population-wide behaviour change: Concordance of 10-year trends in self-reported and observed sun protection

Abstract

Objectives: Increases in socially desirable responses in self-reports might occur in the context of ongoing public education. We examine concordance of trends in two long-term studies monitoring population impact for SunSmart. Methods: One study employed telephone interviews of Melbourne residents; the other entailed observations at public recreation venues across Melbourne. The studies assessed people's sun protection on identical weekend dates (Nw = 33 dates). Data from five summers between 1992 and 2001 (n ~ 23,000 individuals) were analysed. A body cover index score was calculated for participants on each date. Outcomes were aggregated separately for Saturdays and Sundays by date and yea..