Sample size calculation: Basic principles

Addressing a sample size is a practical issue that has to be solved during planning and designing stage of the study. The aim of any clinical research is to detect the actual difference between two groups (power) and to provide an estimate of the difference with a reasonable accuracy (precision). He...

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Bibliographic Details
Published in:Indian journal of anaesthesia 2016-09, Vol.60 (9), p.652-656
Main Authors: Das, Sabyasachi, Mitra, Koel, Mandal, Mohanchandra
Format: Article
Language:English
Subjects:
Analysis
Effect size
Hypothesis testing
Medical research
Planning
power
Principles
randomized control trial
research hypothesis
Researchers
Review
Sample size
Sampling (Statistics)
Studies
study design
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Summary:Addressing a sample size is a practical issue that has to be solved during planning and designing stage of the study. The aim of any clinical research is to detect the actual difference between two groups (power) and to provide an estimate of the difference with a reasonable accuracy (precision). Hence, researchers should do a priori estimate of sample size well ahead, before conducting the study. Post hoc sample size computation is not encouraged conventionally. Adequate sample size minimizes the random error or in other words, lessens something happening by chance. Too small a sample may fail to answer the research question and can be of questionable validity or provide an imprecise answer while too large a sample may answer the question but is resource-intensive and also may be unethical. More transparency in the calculation of sample size is required so that it can be justified and replicated while reporting.
ISSN:0019-5049
0976-2817
DOI:10.4103/0019-5049.190621