The article by Muhammad Fakhri Ramadhan, Rusydi A. Siroj, and Muhammad Win Afgani discusses the validity and reliability of instruments used in educational research, particularly in quantitative studies. The authors define an instrument as a tool used to measure an object or collect data from a variable, emphasizing that a good instrument must be both valid and reliable. Validity is categorized into content validity, construct validity, and empirical validity, while reliability is assessed using KR-20 for dichotomous item scores and Alpha coefficient for polytomous item scores. The interpretation of reliability coefficients is relative, without an absolute minimum threshold, but they provide information on the relationship between observed and true scores. The article outlines the importance of valid and reliable instruments in ensuring accurate measurements. It explains that validity ensures the instrument measures what it is intended to measure, while reliability ensures the consistency of measurements. The authors also detail the methods for assessing validity and reliability, including the use of correlation coefficients and statistical formulas. In conclusion, the authors recommend that researchers, especially beginners, use valid instruments for measuring manifest variables and those valid based on construct and criterion validity for latent variables. They emphasize the importance of using appropriate formulas to determine item validity and instrument reliability, and suggest interpreting reliability coefficients appropriately. The article provides a comprehensive guide for researchers to ensure the quality and reliability of their instruments in educational research.The article by Muhammad Fakhri Ramadhan, Rusydi A. Siroj, and Muhammad Win Afgani discusses the validity and reliability of instruments used in educational research, particularly in quantitative studies. The authors define an instrument as a tool used to measure an object or collect data from a variable, emphasizing that a good instrument must be both valid and reliable. Validity is categorized into content validity, construct validity, and empirical validity, while reliability is assessed using KR-20 for dichotomous item scores and Alpha coefficient for polytomous item scores. The interpretation of reliability coefficients is relative, without an absolute minimum threshold, but they provide information on the relationship between observed and true scores. The article outlines the importance of valid and reliable instruments in ensuring accurate measurements. It explains that validity ensures the instrument measures what it is intended to measure, while reliability ensures the consistency of measurements. The authors also detail the methods for assessing validity and reliability, including the use of correlation coefficients and statistical formulas. In conclusion, the authors recommend that researchers, especially beginners, use valid instruments for measuring manifest variables and those valid based on construct and criterion validity for latent variables. They emphasize the importance of using appropriate formulas to determine item validity and instrument reliability, and suggest interpreting reliability coefficients appropriately. The article provides a comprehensive guide for researchers to ensure the quality and reliability of their instruments in educational research.