Anne Fleur Kortekaas-Rijlaarsdam

CHAPTER 4 88 the influence of MPH: For math productivity the effect of MPH reduced from β = 1.95 (p < .001) to β = 1.41 (p = .007). To ensure that age did not alter the effects of parent- rated self-perceived competence and MPH on math productivity, we also performed the analyses with age as a moderator. Age did not moderate the effects of MPH on any of the math outcomes (all p -values > .05). To quantify the influence of parent-rated self-perceived competence as a partial mediator of the effects of MPH on math productivity, we performed multilevel mediation analysis using GLMM. The results showed that parent-rated self-perceived competence was a significant mediator of the effects of MPH on math productivity: For β a (effect of MPH on parent-rated self- perceived competence) = 1.06 (SE = .36) and β b (effect of parent-rated self-perceived competence on math productivity) = 0.53 (SE = .16), the product term β a β b was 0.56 (SE = .26) with a 95% CI of [.13, 1.15], not including zero. Table 4.1 Group Characteristics of the ADHD and TD Group ADHD (N=63) TD (N=67) ADHD v TD Percentage boys ( N ) 68.25 (43) 59.70 (40) χ 2 =1.03 M SD M SD Age 10.49 1.24 10.16 1.32 t =-1.43 Estimated IQ 97.68 13.82 106.10 12.93 t =3.45** DBD parents Inattention 17.46 4.40 3.78 2.98 t =-20.86** Hyperactivity/Impulsivity 13.21 5.32 3.06 2.75 t =-13.78** ODD 7.21 4.28 CD 1.68 2.43 DBD teacher Inattention 16.40 4.88 Hyperactivity/Impulsivity 11.89 6.91 ODD 4.92 4.82 CD 1.14 2.24 DISC parents Inattention 7.83 1.16 Hyperactivity/Impulsivity 6.22 2.40 ODD 2.95 2.29 CD 0.46 1.08 Note . ADHD Attention-deficit hyperactivity disorder; TD Typically developing controls; DBD Disruptive Behavior Disorder rating scale; DISC Diagnostic Interview Schedule for Children, ODD Oppositional defiant disorder; CD Conduct disorder **p<.01