How to Calculate Sample Size for Different Study Designs in Medical Research?
Open accessAbstract
Calculation of exact sample size is an important part of research design. It is very important to understand that different study design need different method of sample size calculation and one formula cannot be used in all designs. In this short review we tried to educate researcher regarding various method of sample size calculation available for different study designs. In this review sample size calculation for most frequently used study designs are mentioned. For genetic and microbiological studies readers are requested to read other sources.
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The sample size was determined using the sample size formula for cross-sectional surveys, with absolute precision 0.04, proportion 50%, and 20% attrition, giving a minimum of 720 respondents.
“The number of the questionnaire distributed in this study was determined using the sample size formula for cross-sectional surveys [27] calculated by adopting: n = Zα2P(1 − P) ÷ d2. The absolute precision (d) and the proportion of consumers with satisfactory knowledge/practices (P) were taken as 0.04 and 50% [28], respectively. We included attrition of 20% to give the minimum number of respondents”
From Knowledge and self-reported food safety practices among meat consumers in Ilorin, Nigeria. (2022) · cites this paper as [27]
The sample size was calculated based on a formula for cross-sectional studies with a 95% confidence level, margin of error 5%, and infinite population.
“The number of participants calculated based on a formula of cross-sectional studies to calculate the sample size with a 95% confidence level, the margin of error was set at 5%, and the population size was infinite [16].”
From An extensive survey of radiographers from the Middle East and India on artificial intelligence integration in radiology practice (2021) · cites this paper as [16]
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“The number of the questionnaire distributed in this study was determined using the sample size formula for cross-sectional surveys [27] calculated by adopting: n = Z α 2 P (1 − P ) ÷ d 2 .”
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- Authors
- Charan, J., & Biswas, T.
- Affiliations
- Government Medical College (IN)
- Independent Researcher, Kolkata, West Bengal, India
- Corresponding author
- Charan, Jaykaran
- Venue
- Indian Journal of Psychological Medicine
- Publisher
- SAGE Publications
- Published
- 2013-04
- Volume
- 35
- Issue
- 2
- Pages
- 121-126
- ISSN
- 0253-7176 (ISSN-L)
- 0975-1564
- PMC
- PMC3775042
- OpenAlex
- W2088580357
- Cited by
- 3,455
- References
- 9
- Citations by year
- 2026: 373 · 2025: 457 · 2024: 529 · 2023: 517 · 2022: 460 · 2021: 392 · 2020: 278 · 2019: 186 · 2018: 123 · 2017: 74 · 2016: 41 · 2015: 18 · 2014: 5 · 2013: 1
- FWCI
- 19.06
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Licence
- Locations
- Indian Journal of Psychological Medicine (publishedVersion)
- Europe PMC (PubMed Central) (publishedVersion, cc-by-nc-sa)
- PubMed Central (publishedVersion, cc-by-nc-sa)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Epidemiology
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods in Clinical Trials
- Health Sciences › Health Professions › Health Information Management › Methodologies in Health Research and Practice
- Keywords
- sample size determination, research design, statistical power, genetic research, microbiological analysis
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