Main Article Content
Educational constructs change over time to reflect developments in research and educational approaches. To illustrate the process, this article aims to examine validity and reliability, which are important concepts to justify research quality. Originally, validity and reliability were applied to quantitative research. However, these criteria can not be equally applied to qualitative research studies which differ in terms of their theoretical foundations and research aims. The unclear use of these concepts might lead to inappropriate research design or evaluation. This paper, therefore, first examines two different theoretical foundations underlying these two research traditions. It then analyses the subtle variations to clarify the notions of reliability and validity. Some implications are made for researchers to flexibly employ these criteria to enhance their research rigor.