Dorien Bangma

FDM AND CURRENT SYMPTOMS OF ADHD | 191 discontinued the study, 51.9% (n = 41) were from the online research panel and 48.1% (n = 38) of the participants were from the social network source. Since a financial compensation as received by the participants from the online research panel could serve as an external motivation, a validation check was performed in this group. Based on the performances on three validity scales of the Behavior Rating Inventory of Executive Function Adults (BRIEF-A; i.e., negativity, infrequency and inconsistency; Roth et al., 2005; Scholte & Noens, 2011), 5.0% of participants (n = 74) were excluded from the sample. Another 2.0% of participants (n = 30) were excluded from the sample because of other reasons (i.e., age below 18, age was unclear or no Dutch nationality). The remaining sample of 1292 participants were used in current study, of which 36.7% (n = 474) were recruited via the online research panel. By using unique ID codes, it was not possible for participants that were recruited via the research panel to repeat the study for extra financial compensation. Participants had to sign an informed consent prior to participation and were debriefed after completing the questionnaires. Questionnaires were presented in a fixed sequence to all participants (i.e., personal financial situation, IBQ, NEO- FFI, BDI-II-NL, FDS and ARS). For the participants in the research panel the BRIEF-A was added after the ARS. The study was approved by the Ethical Committee of Psychology of the University of Groningen, the Netherlands. Data analyses Group comparisons. To examine group differences in impulsive buying and the use of financial decision styles, Analyses of Variance (ANOVA) have been conducted with the total score and the scores on the subscales of the IBQ and of the FDS as dependent variables, respectively. Post-hoc Bonferroni analyses were conducted when significant group differences were found. In addition, to evaluate group differences in participants’ personal financial situation, Pearson’s chi-square analyses were conducted for variables related to debts, receiving social security, saving money, saving for retirement and owning a house. Differences in income between groups were evaluated using a Kruskal-Wallis test and group differences on the variable ‘free money to spend’ were evaluated with an ANOVA. For all post-hoc analyses, effect sizes and 95% confidence intervals (95% CI) were calculated and interpreted as small (d = 0.20), medium (d = 0.50) and large (d = 0.80; Cohen, 1988). Results were considered significant with an alpha of ≤ .05. Besides a Bonferroni correction in the post-hoc analyses, no further correction for alpha was applied, since current analyses partly replicate previous research in adults with ADHD (Bangma et al., 2019) and smaller effects can be assumed because of the use of a community sample. Predicting financial decision-making. To examine the relation between impulsive buying, the use of financial decision styles and symptoms of ADHD, and to determine the potential influence of personality and symptoms of depression on this relation, nine hierarchical linear regressions were performed in the whole sample (n = 1292) with the four IBQ and five FDS scores as dependent variables. First, to control for the potential effects of age (in years), sex (male/female), level of education (Verhage, 1964) and annual income on impulsive buying and the use of financial decision styles, these independent variables were included in the first model (method: enter). To evaluate the potential effects of symptoms of depression and the Big