[영문]This paper examines the use of parallel analysis, a more accurate factor retention criterion, in order to increase the effectiveness of policy interventions. Environmental factors that are likely to affect the propensity of a community to walk were examined. Results from parallel analysis are compared to those obtained by using the eigenvalue qqqgt; 1 rule. A principal components analysis on 14 variables was performed. The factors retained after using the eigenvalue qqqgt; 1 rule were compared to the factors retained after using parallel analysis. The eigenvalue qqqgt; 1 rule led to the retention of nearly twice the number of latent factors as did the use of parallel analysis. The use of the eigenvalue qqqgt; 1 rule in research may mislead policy makers to focus on trivial interventions. They are urged to use parallel analysis for obtaining more effective interventions