Abstract :
The graded response model (GRM), which is
based on item response theory (IRT), was used to evaluate
the psychometric properties of the inattention and hyperactivity/
impulsivity symptoms in an ADHD rating scale. To
accomplish this, parents and teachers completed the DSMIV
ADHD Rating Scale (DARS; Gomez et al., Journal of
Child Psychology and Psychiatry, 40, 265–274, 1999) for a
group of 1,475 primary school-aged children. The results
for the discrimination parameters showed that all symptoms
for both groups of respondents were generally good for
discriminating their respective latent traits. For virtually all
symptoms, their threshold values showed moderate to large
increases in the level of the latent trait at each subsequent
response dichotomy, with the symptoms being especially
good at representing the appropriate traits from mean to
moderately high trait levels. The item information function
values for most symptoms indicated reasonable reliability
from, approximately, the mean trait levels to moderately
high trait levels. These findings indicate good psychometric
properties for the parent and teacher ratings of the DARS.
The implications of the findings for the use of the DARS
and other similar scales are discussed
