Bridging Theory and Practice: Study of Informal Inferential Reasoning Instrument Development for Junior High School Students

The goal of this study is to create a valid and reliable informal inferential reasoning tool. This is Research and Development (R D) research that employs a modified Plomp model. An initial inquiry phase, a prototype phase, and an assessment phase comprise the development stages. The content validity test was conducted by two specialists, one in the field of Mathematics Education and one in the field of Mathematics. The trial featured a total of 28 class IX pupils from SMPN 8 Mataram. The product moment correlation was used to assess construct validity, while the Cronbach's Alpha coefficient was used to assess reliability. This study produced an informal inferential reasoning instrument with six question items based on three different contexts relevant to the challenge of comparing two groups of data. This instrument is suitable for usage, according to all validators. The trial findings also reveal that all items in this instrument meet the validity and reliability criteria.