31 March 2012

Standard error of the mean (SEM) in Excel

For reasons that I don't quite understand, Excel does not have a function for calculating the standard error of the mean (SEM). Every time that I want to create a figure with error bars, I have to type in the calculation manually.

SEM is the standard deviation of the sample-mean estimate of a population mean. 

SEM is calculated by taking the standard deviation and dividing it by the square root of the sample size. In Excel, this is calculated using the following formula: