Differential Item Functioning Analysis of ASKSP-R with School Psychologists and Speech-Language Pathologists.
Two ASKSP-R items are biased between school psychologists and SLPs, so remove or adjust them before comparing group scores.
01Research in Context
What this study did
Shahid et al. (2025) checked if the ASKSP-R autism-knowledge quiz works the same way for school psychologists and speech-language pathologists. They ran a DIF analysis on answers from both groups.
DIF means one item is harder for one group even when both groups know the same amount. The test should be fair across jobs.
What they found
Items 14 and 15 on the ASKSP-R showed DIF. School psychologists and SLPs with equal knowledge had different odds of getting those items right.
The authors say the two items are biased, most likely because training programs cover those facts differently.
How this fits with other research
McClain et al. (2019) built the earlier ASKSG for the general public. The new ASKSP-R is the professional cousin, so the 2025 paper is the next step in the same scale family.
Vassos et al. (2023) also found item bias in a youth flourishing scale for autistic kids. Both studies use DIF to catch unfair items, just in different tests.
Kaat et al. (2025) report their new DASCA caregiver scale shows almost no DIF. Their clean result highlights why spotting bias early matters and shows the ASKSP-R still has fixable flaws.
Why it matters
Before you compare ASKSP-R scores from an SLP team to a school psych team, drop items 14 and 15 or treat them as separate. The bias can flip who looks more knowledgeable and steer hiring or training choices the wrong way. A quick item review keeps your data honest and protects kids from underinformed staff.
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02At a glance
03Original abstract
PURPOSE: The current study aims to expand on existing psychometric information related to the Autism Spectrum Knowledge Scale Professional Version-Revised (ASKSP-R; McClain et al., 2019). Specifically, the study addresses two research questions: (1) Which items on the ASKSP-R show evidence of differential item functioning (DIF) between school psychologists (SPs) and speech-language pathologists (SLPs)? and (2) To what extent do ASKSP-R score distributions differ between SPs and SLPs? METHOD: Differential item functioning analysis was used to assess whether items in the measure function similarly across two groups with comparable levels of autism knowledge. Data were collected as part of a larger project examining the current state of autism knowledge among school-based professionals that frequently work with autistic children. The sample included in the study consisted of School Psychologists (n = 210) and Speech-Language Pathologists (n = 202) who completed a demographic questionnaire and the ASKSP-R measure. RESULTS: Results indicated that two items (14 & 15) functioned differently across the two professional groups. CONCLUSION: Potential explanations for item bias are discussed pertaining to training differences and focus of knowledge areas, along with suggestions for revising the measure.
Journal of autism and developmental disorders, 2025 · doi:10.21203/rs.3.rs-6184251/v1