ADHD Parent and Teacher Symptom Ratings: Differential Item Functioning across Gender, Age, Race, and Ethnicity.

Parent and teacher ratings of the two attention-deficit/hyperactivity disorder (ADHD) symptom dimensions (i.e., inattention, hyperactivity-impulsivity) have been found to differ across child gender, age, race, and ethnicity. Group differences could be due to actual variation in symptomatic behaviors but also could be due to measurement items functioning differently based on child characteristics. This study extended prior investigations establishing measurement invariance at the symptom dimension and item levels, by examining possible measurement variance across child demographic characteristics at the item level (i.e., differential item functioning [DIF]) in two large national samples. Using the Rasch rating scale model (Andrich Psychometrika, 43, 561-73, 1978), we examined DIF of the 18 ADHD symptoms in samples of 2079 children (n = 1037 males) from 5 to 17 years old (M = 10.7; SD = 3.8) rated by parents and 1070 children (n = 535 males) aged from 5 to 17 years old (M = 11.5; SD = 3.5) rated by teachers. All but six ADHD symptom items showed DIF across child age, gender, race (Black vs. White), and ethnicity with more items showing DIF for age than for gender, race, or ethnicity. For child gender and age, more items showed DIF for parent than for teacher ratings. More items showed DIF across racial groups for teacher than for parent ratings. Only two parent- and teacher-rated items showed DIF for ethnicity. Implications of findings for practice, research, and future iterations of ADHD diagnostic criteria are discussed.