Concurrent validity and classification accuracy of the Leiter and Leiter-R in low-functioning children with autism.
Leiter-R is valid for most nonverbal autistic kids, but keep the original Leiter handy for very low-functioning younger ones.
01Research in Context
What this study did
The team gave both the old Leiter and the newer Leiter-R to the same group of low-functioning children with autism. They wanted to see if the two tests gave the same IQ picture.
Each child took both tests within a short window. The study then compared the scores head-to-head.
What they found
The scores lined up well. The correlation was 0.87, and the average difference was tiny.
Still, ten kids had big gaps between the two tests. These were mostly the youngest and lowest-functioning children.
How this fits with other research
Constantino et al. (2003) also checked concurrent validity that year. They found the 15-minute SRS matched the long ADI-R about as well as the Leiter pair matched each other.
Parks (1983) warned that early autism scales had good reliability but weak validity. The new Leiter-R data show progress: validity is now strong for most kids.
Boudreau et al. (2015) saw mixed validity for the PDDBI. Their Autism Composite did not line up with CARS. In contrast, the Leiter-R showed clean alignment with its parent test.
Why it matters
You can swap in the Leiter-R for the old Leiter and trust the score—unless the child is very young and low-functioning. For those kids, keep both tests on the shelf. If scores differ, use the original Leiter or add a second measure before big decisions like classroom placement.
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02At a glance
03Original abstract
The concurrent validity of the Leiter International Performance Scale (Leiter) and Leiter International Performance Scale-Revised (Leiter-R) was examined in a sample of children with autism who could not be assessed with more traditional measures of intelligence (e.g., the Wechsler scales). The sample consisted of 26 children ranging in age from 4 to 16 years. The correlation between the Leiter scales was high (r = .87), and there was a difference of 3.7 points between the two mean scores, nonsignificant at both statistical and clinical levels. However, significant intraindividual discrepancies were present in 10 cases, 2 of which were both large (24 and 36 points) and clinically meaningful. The mean profile of performance on Leiter-R subtests is also presented for this sample of children with autism, to allow for comparison with other groups. Based on the results of this initial evaluation, together with the current normative data, good psychometric properties, and availability of global and subtest scores with the Leiter-R, the instrument is generally recommended for use with children with autism. However, because of changes in the design of the Leiter-R, there may be greater clinical success with the original Leiter for those children who are very low functioning and severely affected, particularly younger children.
Journal of autism and developmental disorders, 2003 · doi:10.1023/a:1022274219808