Assessment of Intellectual Disability: An Examination of Current State Special Education Guidelines for Intelligence and Adaptive Behavior.

Assessment and identification of Intellectual Disability (ID) under the IDEA 2004 requires the measurement of both intelligence and adaptive behavior and the presence of significantly subaverage general intellectual functioning, existing concurrently with deficits in adaptive behavior and manifested during the developmental period that adversely affect a student's educational performance. Best practices in the assessment of ID call for the use of appropriate individually administered, standardized, norm-referenced measures of intelligence and adaptive behavior. Full-scale intelligence test scores and adaptive behavior composite scores and domains scores should all be accompanied by confidence intervals due to measurement error. Best practices in the measurement of adaptive behavior suggest reliance on the composite score in the identification of ID over domain scores given the lower reliability and validity of the domain scores with some measures. Furthermore, the collection of data from multiple informants is necessary due to measurement error and the understanding that adaptive behavior is often situationally specific. This practice also reduces the likelihood of overidentification and may result in the identification of specific skills that merit further assessment and intervention. This study expands past research by examining current state special education guidelines based on IDEIA and their alignment with best practices in assessment across all U.S. states and the District of Columbia (DC) for the assessment of ID. Aggregated and disaggregated data pertaining to special education guidelines and recommendations are examined, including cut-scores and confidence intervals, information specific to composite adaptive behavior scores versus domain scores, and multiple informants. Limitations, implications, and recommendations based on best practices in assessment for educational professionals involved in the assessment of ID are discussed. [ABSTRACT FROM AUTHOR]