# 3.163 FAQ-1082 What's the difference between SE and SEM?

Last Update: 1/11/2021

In regression calculation, SE (Standard Error) of the fitted parameter is the same as SD (Standard Deviation). Refer to this FAQ for details. However, SEM (Standard Error Mean) is not used in regression. It is mainly used in statistics comparing a group of data.

In statistics, SD represents the dispersion of a group of data, while SEM is "the standard deviation of the mean" calculated by the following equation.

$SEM = \frac {SD}{ \sqrt{n}}$

It provides information to determine how well the mean is if you repeat the measure many times. Generally speaking, SD and SEM are very different.

Keywords:SE, SD, SEM, parameter, nonlinear curve fit, standard error of mean, standard deviation