title: What to use to express the variability of data: Standard deviation or standard error of mean?
abstract: Statistics plays a vital role in biomedical research. It helps present data precisely and draws the meaningful conclusions. While presenting data, one should be aware of using adequate statistical measures. In biomedical journals, Standard Error of Mean (SEM) and Standard Deviation (SD) are used interchangeably to express the variability; though they measure different parameters. SEM quantifies uncertainty in estimate of the mean whereas SD indicates dispersion of the data from mean. As readers are generally interested in knowing the variability within sample, descriptive data should be precisely summarized with SD. Use of SEM should be limited to compute CI which measures the precision of population estimate. Journals can avoid such errors by requiring authors to adhere to their guidelines.
authors.affiliation: Shrimohini Centre for Medical Writing and Biostatistics Pune, Maharashtra, India.
authors.forename: Mohini P
authors.initials: MP
authors.lastname: Barde
authors.forename: Prajakt J
authors.initials: PJ
authors.lastname: Barde
keywords: Standard deviation; confidence interval; standard error of mean