Principles of sample size calculation.
In most areas in life, it is difficult to work with populations and hence researchers work with samples. The calculation of the sample size needed depends on the data type and distribution. Elements include consideration of the alpha error, beta error, clinically meaningful difference, and the variability or standard deviation. The final number arrived at should be increased to include a safety margin and the dropout rate. Over and above this, sample size calculations must take into account all available data, funding, support facilities, and ethics of subjecting patients to research.
Department of Clinical Pharmacology, Seth GS Medical College and KEM Hospital, Parel, Mumbai, Maharashtra, India. njgogtay@hotmail.com
Nithya J
NJ
Gogtay
D002986:Clinical Trials as Topic; D003627:Data Interpretation, Statistical; D006801:Humans; D018401:Sample Size