On Using Standard Deviation or Standard Error of the Mean.

The mean value is commonly used as a measure of central tendency. It is frequently reported along with either the standard deviation (SD) or the standard error of the mean (SEM). While the SD reflects the dispersion of the data in both the sample and population, SEM indicates the precision of the mean. SEM is not commonly used in reporting science; however, the 95% confidence interval, which is calculated based on SEM, is frequently reported in scientific literature.