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

    16 Citations (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

    Bibliographical note

    Publisher Copyright:
    © The Korean Society of Anesthesiologists, 2020.


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

    ASJC Scopus subject areas

    • Anesthesiology and Pain Medicine


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