Sample size calculation using G*Power software

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Abstract

Sample size calculation is a critical step in planning a research project to obtain valid and generalizable results in biomedical sciences. It enables researchers to reach a balance between time, resources, and ethical considerations when planning and conducting research. Statistical software can assist in calculating sample size, but calculation method depends on the data characteristics and the research question.
This article presents a practical tool for calculating the required sample size for studies that aim to compare measures of central tendency for several research questions using the G*Power software. Sample size calculation for Student’s unpaired t-test, oneway analysis of variance (ANOVA), as well as their non-parametric analogs – Wilcoxon and Mann–Whitney tests are presented. The article walks readers step by step through sample size calculations for the abovementioned situations using practical examples. Therefore, this paper has a potential to become a valuable resource for junior researchers who are at the planning phase of their research. It serves as a practical guide for calculating the required sample size for parametric and nonparametric methods of analysis to test statistical hypotheses about the equality of measures of central tendency in unpaired groups.

About the authors

E. A. Krieger

Northern State Medical University

Email: kate-krieger@mail.ru
ORCID iD: 0000-0001-5179-5737
SPIN-code: 2686-7226

Ekaterina A. Krieger — Cand. of Sci. (Med.), Associate  Professor, Research fellow of the International Research  Competence Centre, Central Scientific Research  Laboratory

51 Troitskiy Av., Arkhangelsk, 163069

Russian Federation

S. N. Drachev

Northern State Medical University

Email: drachevsn@mail.ru
ORCID iD: 0000-0002-1548-690X
SPIN-code: 3879-8612

Sergei N. Drachev — Cand. of Sci. (Med), MPH,  Associate Professor at the Department of Prosthodontics

51 Troitskiy Av., Arkhangelsk, 163069

Russian Federation

N. A. Mitkin

Northern State Medical University

Email: n.a.mitkin@gmail.com
ORCID iD: 0000-0002-0027-8155

Nikita A. Mitkin — Junior researcher, International Research Competence, Central Scientific Research Laboratory, Assistant of the Department of Scientific Research Methodology

51 Troitskiy Av., Arkhangelsk

Russian Federation

V. A. Postoev

Northern State Medical University

Email: ispha@nsmu.ru
ORCID iD: 0000-0003-4982-4169

Vitaly A. Postoev – Cand. of Sci (Med.), Acting Head of the Department of Research Methodology, Head of Arkhangelsk School of Public Health

Troitskiy Ave., 51, Arkhangelsk, 163069

Russian Federation

A. M. Grjibovski

Northern State Medical University

Author for correspondence.
Email: A.Grjibovski@yandex.ru
ORCID iD: 0000-0002-5464-0498
SPIN-code: 5118–0081

Andrej M. Grjibovski — Doctor of Medicine, Head of the Directorate for Research and Innovations, Director of the Central Scientific Research Laboratory

51 Troitskiy Av., Arkhangelsk, 163069

Russian Federation

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Copyright (c) 2023 Krieger E.A., Drachev S.N., Mitkin N.A., Postoev V.A., Grjibovski A.M.

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This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
 


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