Which of the following is NOT a qualitative research method?

Experimental design is not a qualitative research method because it focuses on quantifiable data and aims to establish causation through statistical analysis. Qualitative research methods, such as case studies, phenomenology, and ethnography, emphasize understanding human experiences, social phenomena, and cultural contexts through non-numerical data. These qualitative approaches allow researchers to explore the depth and complexity of subjects, often using interviews, observations, or textual analyses to derive insights. In contrast, experimental design typically involves controlled environments, manipulation of variables, and the use of measurements that yield numerical results, which distinguishes it from qualitative methods.