Abstract: The selection of outcome measures should be based on the study design, anticipated results, and available resources. Biological parameters, analysis of economic benefits, and life-quality assessment are commonly employed outcome measures. Outcome measures, observation method, and evaluation method correlate with the study design and affect the sample size estimation. The sample size should be determined according to various factors, including power, significance level, expected effect sizes and standard deviation in the case of continuous variables. In clinical research, rationally selecting outcome measures and scientifically estimating sample sizes might markedly improve the reliability and feasibility of the study results.