A New Brief Scale to Measure Optimism.

This research was done to find if using maximum likelihood could reduce the Interactive Optimism Scale-Garcia to a new valid and reliable shorter version. There were 502 adults: 263 women and 239 men (Mage = 34.67, SD = 12.27). It was used in confirmatory factor analysis. A four-item scale is obtained, having excellent goodness of fit: [χ2/df = .609, GFI (Jöreskog and Sörbom's Goodness-of-Fit Index) = .999, NFI (Normed Fit Index) = .999, CFI (Bentler's Comparative Fit Index) = 1.000, RMSEA (Steiger-Lind root mean square error of approximation) = .000 (90% CI = .0001, .077); SRMR (standardized root mean square residual) = .007], as well as factorial invariance across sexes; the scale has good internal consistency (ω = .869, α = .858, ordinal α = .906). Brief Interactive Optimism Scale-G correlates significantly with self-esteem (r = .779, p < . 01, 95% CI [.816, .736]), depression (r = -.810, p < .01, 95% CI [.843, .772]), and psychopathy (r = -.670, p < . 01, 95% CI [.723, .611]). In conclusion, Brief Interactive Optimism Scale-G is a good option for measuring optimism in Mexicans.