Dorien Bangma

192 | CHAPTER 8 Five personality traits, the total scores on the BDI and the five NEO-FFI personality traits, respectively, were included in the second model of the regression analyses (method: enter). Finally, the ARS total score reflecting current symptoms of ADHD was included in the third model. The ARS and BDI scores were LOG transformed to control for the strong positive skewness in these variables. After transformation, these variables showed a trend towards a normal distribution. R 2 / sr 2 were used as measures of effect size and interpreted as small ( R 2 / sr 2 = below .08), medium ( R 2 / sr 2 = between .11 and .27) or large ( R 2 / sr 2 = above .30; Fritz et al., 2012). When the ARS total score significantly contributed to the model, the hierarchical regression was repeated including the ARS total scores (i.e., current symptoms) of the inattentive items and the hyperactive/impulsive items separately. Because of the explorative approach of the regression analyses with the use of a relatively large number of independent variables, the inclusion of a relatively large sample and in order to control for multiple testing, a conservative alpha (p ≤ .001) was used for these analyses to reduce the change of overoptimism or type 1 errors. Results Group comparisons Impulsive buying. Significant group differences were found on the IBQ total score and for both the cognitive and affective subscales of the IBQ (Table 8.2). The ADHD group obtained significantly higher scores on the IBQ cognitive subscale compared to both the No ADHD group ( Mean Difference (MD) = 2.7; Standard Error (SE) = .88; p = .015; d = 0.54, 95% CI [0.22; 0.86]) and the Subthreshold ADHD group ( MD = 2.5; SE = .92; p = .039; d = 0.40, 95% CI [0.07; 0.73]). Furthermore, the Adult-only ADHD group obtained significantly higher scores compared to the No ADHD group on the IBQ total score ( MD = 4.3; SE = 1.5; p = .018; d = 0.47, 95% CI [0.18; 0.76]) and on both subscales (IBQ cognitive subscale: MD = 2.2; SE = .80; p = .033; d = 0.45, 95% CI [0.16; 0.73] and IBQ affective subscale: MD = 2.1; SE = .79; p = .046; d = 0.41, 95% CI [0.12; 0.70]). No significant differences were found regarding the other group comparisons and groups also did not differ in the situational subscale of the IBQ (Table 8.2). Financial decision styles. Significant group differences were found on the FDS avoidant subscale and the FDS spontaneous subscale (Table 8.2). For the FDS avoidant subscale, significantly higher scores were obtained by both the ADHD group and the Adult-only ADHD group compared to the No ADHD group ( MD = 1.8; SE = .62; p = .030; d = 0.48, 95% CI [0.16; 0.79] and MD = 3.3; SE = .57; p < .001; d = 0.90, 95% CI [0.60; 1.19]; respectively). The scores on the FDS avoidant subscale of the Adult-only ADHD group were also significantly higher compared to the Subthreshold ADHD group ( MD = 2.3; SE = .60; p = .001; d = 0.56, 95% CI [0.25; 0.86]). No significant differences were found on the FDS avoidant subscale between the other groups. With regard to the FDS spontaneous subscale, the ADHD group obtained significantly higher scores compared to the Subthreshold ADHD group ( MD = 1.3; SE = .42; p = .009; d = 0.50, 95% CI [0.17; 0.83]) and the No ADHD group ( MD = 1.5; SE = .40; p =