Validity and Reliability of Mathematics Intervention Instrument Based on the Learning Style of Students with Learning Disability (IMGAP) Using Rasch Assessment Model

Abstract

Survey questionnaires have been widely used to measure important outcomes in special education. However, the reliability and validity of these questionnaires are often measured using the Classical Test Theory approach. In the meantime, Rasch Analysis based on Item Response Theory provides a better alternative for examining the psychometric quality of rating scales and informing scale improvements. This article outlines a six-step process for using Rasch Analysis to review the psychometric properties of a rating scale, namely item functional inspection, reliability and item-respondent separation, polarity and suitability of items for construct measurement, and the standard residual correlation values.  The questionnaires were distributed to 140 special education (learning disabilities) teachers. The final analysis found that no items were dropped from the questionnaire. Thirty-nine items were deemed suitable for evaluating constructs related to learning styles-based mathematical intervention for students with learning disabilities. The findings from the analysis have statistically proved that the items in this instrument have a high degree of validity and reliability as well as suitable to be used on special education teachers for learning disabilities in determining the importance of considering learning styles as one of the important factors when conducting mathematical interventions of students with learning disabilities.