Development of a preschool developmental assessment scale for assessment of developmental disabilities.
The 40-item PDAS cognitive scale gives BCBAs a fast, reliable way to spot thinking delays in preschoolers.
01Research in Context
What this study did
Leung et al. (2010) built a new 40-item test for preschool thinking skills. They call it the Preschool Developmental Assessment Scale, or PDAS.
The team checked if the test scores lined up with a tough math model called Rasch. They also looked at whether the test could tell the difference between kids with developmental delays and kids who are typically developing.
What they found
The PDAS cognitive part passed every Rasch rule. Internal consistency was high at KR-20 = .93.
Most important, kids with developmental disabilities scored much lower than same-age peers. The test cleanly split the two groups.
How this fits with other research
Lubomir et al. (2022) did the same thing for social skills. Their 3-scenario SoROS also separates preschoolers with ASD from peers. Both scales give clinicians short, low-cost screeners.
Narzisi et al. (2013) and Limberg et al. (2017) took a different path. They used the CBCL 1½-5 parent form instead of making a new test. Their Withdrawn and PDD cut-offs also flag ASD risk, showing you can either build new or trim existing tools.
Palka Bayard de Volo et al. (2021) trimmed an old language test down to 39 items, much like Cynthia trimmed the PDAS to 40. Both teams proved shorter forms keep the power.
Why it matters
If you evaluate preschoolers, you now have a 40-item cognitive screener that is quick, reliable, and free of floor effects. Use it at intake to spot kids who need deeper testing. Pair it with social or language screeners like SoROS or CCC-R for a fuller picture without long waitlists.
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02At a glance
03Original abstract
The aim of this paper was to describe the development of the cognitive domain of the Preschool Developmental Assessment Scale (PDAS) for assessment of preschool children with developmental disabilities. The initial version of the cognitive domain consisted of 87 items. They were administered to 324 preschool children, including 240 children from preschools and 84 children with developmental disabilities. Initial Rasch analysis results indicated that the fit statistics of 42 of the items were outside the acceptable range. Based on the fit statistics and considering the overall structure of the scale, the revised version consisted of 40 items and this version conformed to the Rasch expectations. The revised 40-item scale could differentiate between children with typical development and children with developmental disabilities. It could also differentiate between children from different age groups. The internal consistency estimate (KR-20) was .93. The cognitive domain of the PDAS is considered a promising developmental assessment tool for assessment of developmental disabilities.
Research in developmental disabilities, 2010 · doi:10.1016/j.ridd.2010.07.004