Description:
OBJECTIVE: ADHD and Hyperkinetic Disorder (HKD) have the same 18 symptoms, covering inattention (IA), hyperactivity (HYP), and impulsivity (IMP). This study was aimed at providing descriptive scores for the different symptom groups in these disorders and how these scores varied by age and gender, the percentages of individuals meeting the symptom thresholds for the different ADHD types and HKD, the factor structure, and gender invariance of these symptoms in adults. METHOD: To accomplish this, 852 adults provided self-ratings for a scale comprising the 18 ADHD/HKD symptoms. RESULTS: The findings showed that age and gender had minimal effects on the ADHD symptoms. Also, in terms of symptom counts, 2% had HKD and 6.3% had ADHD (inattentive = 1.6%, hyperactive-impulsive = 2.7%, and combined type = 2.0%). Confirmatory factor analysis (CFA) provided most support for the three-factor HKD model, involving separate factors for the IA, HYP, and IMP symptoms. This model showed full measurement invariance across gender. CONCLUSION: The theoretical and clinical implications of the findings are discussed.
Description:
Objective: Generalized partial credit model, which is based on item response theory (IRT), was used to test differential item functioning (DIF) for the Diagnostic and Statistical Manual of Mental Disorders (4th ed.), inattention (IA), and hyperactivity/impulsivity (HI) symptoms across boys and girls. Method: To accomplish this, parents completed an ADHD rating scale for 403 boys and 380 girls, between 6 and 11 years of age. Results: The findings indicated no DIF for all the slope parameters for both the IA and HI symptoms. For location parameters, there was no DIF for all the IA symptoms and for seven of the nine HI symptoms. However, the effect sizes for the DIF symptoms were small. Thus, there was good support for gender equivalency for the ADHD symptoms. Conclusion: These findings extend existing data on gender equivalency of ADHD symptoms, obtained using other methodologies for testing measurement equivalency.