These sources collectively examine the methodological complexities of sampling and case selection within qualitative and mixed-methods research. They explore various strategies such as theoretical, purposeful, and realist sampling, emphasizing that researchers must balance theoretical rigor with practical constraints like time and funding. The texts illustrate these concepts through diverse studies, ranging from social determinants of health in unemployed populations to the lived experiences of residents in Mumbai slums. Key discussions highlight the role of gatekeepers in accessing marginalized groups and the nuanced relationship between empirical evidence and the researcher’s own theoretical presuppositions. Additionally, the materials analyze large-scale demographic data, such as the Census of India and UK longitudinal studies, to demonstrate how categories like ethnicity and disability are constructed and transformed over time. Ultimately, the collection serves as a guide for navigating the evolving nature of research design, stressing that analytical depth and credibility are often more vital than large sample sizes.