Tips for troublesome sample-size calculation

Junyong In, Hyun Kang, Jong Hae Kim, Tae Kyun Kim, Eun Jin Ahn, Dong Kyu Lee, Sangseok Lee, Jae Hong Park

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Properly set sample size is one of the important factors for scientific and persuasive re-search. The sample size that can guarantee both clinically significant differences and adequate power in the phenomena of interest to the investigator, without causing excessive fi-nancial 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, ex-amples regarding sample size calculation that are appropriately and incorrectly described in the published papers are presented with explanations.

Original languageEnglish
Pages (from-to)114-120
Number of pages7
JournalKorean journal of anesthesiology
Issue number2
Publication statusPublished - 2020 Apr


  • Biostatistics
  • Effect size
  • Independent t-test
  • P value
  • Power
  • Sample size

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

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