Rasch Model: Quality of Test Instruments to Measure Students’ Ability in Algebra

Abstract

This research is research using a quantitative approach that aims to analyze the quality of the test instrument by using the Rasch model to measure the ability of students in junior high school mathematics courses, especially in Algebra material. The sample used in the study was 37 students. The instrument used is a multiple-choice test with four answer choices consisting of 30 questions. The results obtained from this study there are 27 valid items and 3 invalid items. The reliability of the test score (reliability) of the estimation results using the Rasch model shows that the reliability is included in the good category with a person reliability value of 0.74, item reliability of 0.84 and Cronbach's Alpha of 0.85. For the level of difficulty or difficulty of the items, 7 items are in the very easy category, 7 items are in the easy category, 11 items are in the difficult category and 5 items are in the very difficult category. Of the 30 questions, there is 1 item that must be discarded because the question is too easy. The level of ability of students with serial numbers 18 and 4 is classified as person misfit in the Rasch model. This is because students with serial numbers 18 and 4 have an unusual pattern of answers, namely not being able to answer correctly on items that are classified as easy, but able to answer correctly on items that are classified as difficult.