Study Design, Sample Size Estimation, and Selection of Statistical Method

Study design is the first step of medical research; a well-designed study makes the research valid and reliable. In this chapter, we will introduce the common study designs in medical research—observational and experimental studies (includes laboratory studies and clinical trials). The study design includes both professional and statistical designs. In addition, we will introduce the estimation of sample size (that is an important part of the study design) and the selection of statistical methods.