Reliability and Validity Analysis of Statistical Reasoning Test Survey Instrument using the Rasch Measurement Model

Abstract

This study is an assessment of the reliability and validity analysis of Statistical Reasoning Test Survey (SRTS) instrument using the Rasch Measurement Model. The SRTS instrument was developed by the researchers to assess students' statistical reasoning in descriptive statistics among Tenth Grade science-stream students in rural schools. SRTS was a combination of a subjective test and an open-ended format questionnaire which contained of 12 items. The respondents' statistical reasoning was assessed based on these four constructs: Describing Data, Organizing Data, Representing Data and Analyzing and Interpreting Data. The sample comprised of 115 (76%) girls and 36 (24%) boys aged 15-16 years old from a rural district in Sabah, Malaysia. Overall, the SRTS instrument was found to have a high reliability with a Cronbach's alpha value (KR-20) of 0.81. Results also showed that SRTS has an excellent item reliability and high item separation value of 0.99 and 9.57 respectively. SRTS also has a good person reliability and person separation value of 0.81 and 2.04 respectively. Meanwhile, the validity of the SRTS instrument was appropriately established through the item fit, person fit, variable map, and unidimensionality. In conclusion, this study indicates that the SRTS is a reliable and valid instrument for measuring the statistical reasoning of science-stream students from rural secondary schools.