Theory of Sample Size Determination and Key Informant Characteristics in Qualitative Research

Abstract

This article aims to study (1) the theories regarding the determination of the sample size of key informants in qualitative research, (2) the characteristics of key informants in qualitative research, and (3) the selection process of key informants in qualitative research. Selecting key informants, or participants, in qualitative research is a process that requires integrating both the science and art of the researcher. Qualitative research focuses on understanding specific phenomena within particular groups, events, or processes. Researchers must prioritize selecting key informants based on alignment with the research objectives. Moreover, qualitative research seeks to uncover information unique to specific groups. Therefore, researchers must consider criteria for selecting key informants, such as ensuring alignment with the research objectives. Key informants should provide sufficient insights to comprehensively and fully explain the phenomenon under study. Findings derived from the selection of key informants should lead to clear conclusions, with data that is reliable, credible, and adheres to ethical research principles. Furthermore, the selection of key informants must be strategically planned. This article proposes a theory for determining the size and characteristics of key informants in qualitative research, based on the author’s concepts. It includes methods for selecting key informants that have been studied, tested, and presented by scholars and researchers, along with related research on determining key informant sample sizes in qualitative studies.