Reliability generalization for Childhood Autism Rating Scale.
CARS scores stay steady across decades and raters, so you can trust them for intake decisions—if your team stays trained.
01Research in Context
What this study did
Green et al. (2013) pooled every CARS study from 1980 to 2012. They asked one question: do different teams get the same CARS scores for the same kids?
The meta-analysis looked at two kinds of reliability. Internal consistency: do the 15 items hang together? Inter-rater: do two raters agree when they watch the same child?
What they found
Across all studies, CARS scores showed good internal consistency (.90) and solid inter-rater agreement (.80).
In plain words, the scale hangs together and different raters usually land near the same total score.
How this fits with other research
Carr et al. (2002) had already shown that higher CARS-P scores line up with an autism diagnosis and with parent stress. Green et al. (2013) now show those single-study numbers hold up when you zoom out to 30 years of data.
Williams et al. (2006) found the CAST questionnaire also gives steady scores over two weeks. Together, the two papers tell us both parent-report and clinician-observation tools can be trusted in early-phase research.
Bölte et al. (2008) proved the SRS works across cultures. Green et al. (2013) did the same time-test for CARS. The pair gives you confidence: pick either tool and the psychometric floor is solid.
Why it matters
You can keep using CARS for intake or progress tracking without second-guessing the numbers. Just remember: reliability lives in how you train your raters, not in the form itself. Run a quick double-score once a quarter to keep your team calibrated.
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02At a glance
03Original abstract
The Childhood Autism Rating Scale (CARS) is a popular behavior-observation instrument that was developed more than 34 years ago and has since been adopted in a wide variety of contexts for assessing the presence and severity of autism symptomatology in both children and adolescents. This investigation of the reliability of CARS scores involves meta-analysis and meta-regression of empirical data from reports of original research that made use of CARS between 1980 and 2012. Findings of good internal consistency (.896, 95 % CI .877-.913) and good interrater reliability (.796, 95 % CI .736-.844) support use of CARS at least in early-phase, exploratory research. Evidence of heterogeneity among literature data indicates that reliability is a property of CARS scores and is not intrinsic to the instrument itself. As the first of its kind pertaining to autism, this investigation provides guidance for reviews of other instruments' ratings.
Journal of autism and developmental disorders, 2013 · doi:10.1007/s10803-013-1832-9