The development of diagnostic test instrument to identify physics conceptual understanding of high school students.

A qualified assessment can determine the quality of learning. One type of the assessment that educators or teachers can use is diagnostic test. The focus of this study is to develop a diagnostic test instrument which can be used to identify high school students' conceptual understanding of physics subjects related to the Doppler effect and sound intensity level. This is a type of research and development (R&D) with a 4D model (define, design, develop, disseminate). The subjects of this research were high school students in class XI MIPA in Public Senior High School 3 Solok who had received lessons on sound waves. The data collection technique used is an ordinary multiple choice test instrument. Analysis of quantitative and qualitative by using IRT (Item Response Theory) was applied to the test results. According to the content validity using Aiken's V equation, this instrument was declared to be valid with very good criteria. In line to the Rasch model and the value of INFIT MNSQ and INFIT t, all items in the test instrument were valid. The diagnostic test instrument is also trustful, because the value of reliability of estimate achieves 0.90. Thus, it can be used to identify and analyze the students' conceptual understanding profile. The instrument has thus satisfied the test criteria that are feasible in terms of content, validity, reliability, and empirical evidence. In addition, the results of this conceptual understanding profile are expected to be one of the information for teachers in order to overcome students' difficulties and arrange appropriate learning strategies during the learning process. [ABSTRACT FROM AUTHOR]