The respective nonlinear univariate LGMs for impulsivity, neuroticism, and extraversion demonstrated adequate to excellent fit to the data: impulsivity, χ2(4, N = 483) = 13.91, p < .01, comparative fit index (CFI) = .97, root-mean-square error of approximation (RMSEA) = .07, standardized root-mean-square residual (SRMR) = .05; neuroticism, χ2(4, N = 483) = 10.07, p < .05, CFI = .99, RMSEA = .06, SRMR = .04; extraversion, χ2(4, N = 483) = 22.86, p < .001, CFI = .97, RMSEA = .10, SRMR = .05 (see Loehlin, 2004, on evaluating model fit). As indicated in Table 5, mean-level decreases in all three personality constructs occurred from ages 18 to 35. For impulsivity and neuroticism, results also revealed a significant negative relationship between the intercept and slope (see Table 5), indicating that individuals with higher initial levels of these respective constructs tended to decrease at steeper rates (i.e., have more negative slopes) in these respective constructs compared with those having lower initial levels.
