Allameh Tabataba’i University Quarterly of Educational Measurement 2252-004X 7 24 2016 06 21 introduction of Generalizability theory and describing the process of a measurement study to assessing reliability introduction of Generalizability theory and describing the process of a measurement study to assessing reliability 43 81 7548 10.22054/jem.2017.6144.1186 FA Noor-Ali Farroukhi Laila Bahrami Journal Article 2016 07 15 Background: Recognizing multiple sources of measurement error and estimates each source separately, distinguishes between relative and absolute decisions, distinguishes between fixed and random facets and also the capability of dealing with different D study designs can be mentioned as the strength points of generalizability theory which have no corresponding statuses in classical test theory. Generalizability theory is unknown for our researchers and there are rare researches in this area. <br /> Objective: The Purpose of this article was introduction of generalizability theory and presentation the practical applicability of this theory in assessing the reliability of measurements. <br /> Results: In addition to comparison between classical test theory and generalizability theory, conceptual framework of generalizability theory was explained easily. Also, in this article the process of design, analysis and interpretation of a measurement study in shape of an example with relevant calculations and equations explained in detail in 15 steps to guide researchers and test developers who aimed to assessing reliability.<br /> Conclusion: This article shows that utility of generalizability theory in reliability estimation especially in complicated measurement situations is more than classical test theory. Generalizability theory enables researchers to decrease errors in plan of measurement through optimization proceedings which will increase accuracy in generalization of results. Background: Recognizing multiple sources of measurement error and estimates each source separately, distinguishes between relative and absolute decisions, distinguishes between fixed and random facets and also the capability of dealing with different D study designs can be mentioned as the strength points of generalizability theory which have no corresponding statuses in classical test theory. Generalizability theory is unknown for our researchers and there are rare researches in this area. <br /> Objective: The Purpose of this article was introduction of generalizability theory and presentation the practical applicability of this theory in assessing the reliability of measurements. <br /> Results: In addition to comparison between classical test theory and generalizability theory, conceptual framework of generalizability theory was explained easily. Also, in this article the process of design, analysis and interpretation of a measurement study in shape of an example with relevant calculations and equations explained in detail in 15 steps to guide researchers and test developers who aimed to assessing reliability.<br /> Conclusion: This article shows that utility of generalizability theory in reliability estimation especially in complicated measurement situations is more than classical test theory. Generalizability theory enables researchers to decrease errors in plan of measurement through optimization proceedings which will increase accuracy in generalization of results. https://jem.atu.ac.ir/article_7548_44b5e92446185eddb317d49ff06235c0.pdf