Nagele (1) reviewed 860 articles published in Anesthesia & Analgesia, British Journal of Anesthaesia, Anesthesiology, and European Journal of Anesthesiology during 2001. The aim was to assess how often the variability measure SD (standard deviation) was confused with the uncertainty measure SEM (standarde error of the mean).Of the 860 articles 198 (23%) inappropriately used the SEM to describe the variability in the sample.

The author concludes that journals should provide clearer statistical guidelines on how to report data variability in descriptive statistics.


Nagele P. Misuse of standard error of the mean (SEM) when reporting variability of a sample. A critical evaluation of four anaesthesia journals. Br J Anaesth 2003;90:514-516.