Tips for troublesome sample-size calculation

• Published in: Korean journal of anesthesiology Vol. 73; no. 2; pp. 114 - 120
• Main Authors: In, Junyong, Kang, Hyun, Kim, Jong Hae, Kim, Tae Kyun, Ahn, Eun Jin, Lee, Dong Kyu, Lee, Sangseok, Park, Jae Hong
• Format: Journal Article
• Language: English
• Published: Korea (South) Korean Society of Anesthesiologists 01.04.2020; 대한마취통증의학회
• Subjects: biostatistics; effect size; independent t-test; p value; power; sample size; Statistical Round; 마취과학; Biostatistics; Independent t-test; P value; Sample size; Effect size; Power
• ISSN: 2005-6419; 2005-7563; 2005-7563
• DOI: 10.4097/kja.19497

Properly set sample size is one of the important factors for scientific and persuasive research. The sample size that can guarantee both clinically significant differences and adequate power in the phenomena of interest to the investigator, without causing excessive financial or medical considerations, will always be the object of concern. In this paper, we reviewed the essential factors for sample size calculation. We described the primary endpoints that are the main concern of the study and the basis for calculating sample size, the statistics used to analyze the primary endpoints, type I error and power, the effect size and the rationale. It also included a method of calculating the adjusted sample size considering the dropout rate inevitably occurring during the research. Finally, examples regarding sample size calculation that are appropriately and incorrectly described in the published papers are presented with explanations.