Sampling Methods and Sample Size Determination in Clinical Research: An Educational Review

Clinical research validity depends critically on sound sampling methodology and adequate sample size determination, yet many published studies demonstrate deficiencies in these fundamental aspects. This educational review addresses sampling techniques and sample size calculations in clinical research. The review covers probability sampling approaches, including simple random, systematic random, stratified, and cluster sampling methods, contrasting these with non-probability techniques such as convenience, purposive, snowball, and quota sampling. For each method, we discuss implementation strategies, inherent biases, and appropriate clinical applications. Sample size determination principles are presented…