Differential Item Functioning Analysis of ASKSP-R with School Psychologists and Speech-Language Pathologists

Area of Science:

• Psychometrics
• Special Education
• Clinical Psychology

Background:

• The Autism Spectrum Knowledge Scale Professional Version-Revised (ASKSP-R) is a key tool for assessing autism knowledge.
• Understanding professional knowledge is crucial for effective support of autistic children.
• Previous research has established the ASKSP-R's psychometric properties.

Purpose of the Study:

• To evaluate the psychometric properties of the ASKSP-R.
• To identify differential item functioning (DIF) between school psychologists (SPs) and speech-language pathologists (SLPs).
• To compare ASKSP-R score distributions between SPs and SLPs.

Main Methods:

• Differential Item Functioning (DIF) analysis was employed.
• Data were collected from school-based professionals working with autistic children.
• Participants included 210 School Psychologists and 202 Speech-Language Pathologists who completed the ASKSP-R.

Main Results:

• Two specific items (14 and 15) on the ASKSP-R demonstrated DIF.
• These items functioned differently between the groups of SPs and SLPs.
• No other items showed significant DIF.

Conclusions:

• Item bias in the ASKSP-R was identified between SPs and SLPs.
• Differences in professional training and knowledge focus may explain the observed item bias.
• Suggestions for revising the ASKSP-R are proposed to enhance its validity and reliability.