Validity and reliability of mathematical instruments in online learning using the Rasch measurement model at UM lab school

The existence of the COVID-19 pandemic worldwide has resulted in the implementation of learning changing from offline to online learning. Likewise, the performance of learning at SMA Lab UM is carried out online. Mathematics learning, which has been difficult for the average high school student, is also conducted online. Take online exams for all subjects at Lab High School using the application ThatQuiz. The validity and reliability of the mathematics subject test instrument applied to ThatQuiz need to be known. It is beneficial for the preparation of a better test instrument. In this article, measuring the mathematical test instrument’s validity and reliability used Rasch modeling with Winteps software. Respondents were 67 students of grade 11 for mathematics as many as 25 questions with a choice of answers. This software’s output statistical summary produces person reliability=0.55, Cronbach Alpha 0.63, and reliability items of 0.91. Of these three things, the consistency of student answers is weak, the interaction between students and the overall question items is sufficient, and the quality of the items is good. The construct validity was analyzed based on the correlation of person measure and outfit and MNSQ infit. It was obtained that the MNSQ infit value was between 0.83 and 1.29. At the same time, the MNSQ outfit values range between 0.80 and 3.35. Knowledge of measuring the validity and reliability of a test instrument is needed by the teacher to improve students’ quality of the test instrument.