Standard error (statistics)

The standard error (SE), in statistics, is a measure of spread for a sample of data. Mathematically, the SE is the standard deviation divided by the square root of the sample size.

Standard error vs. standard deviation
The standard error is commonly confused with the standard deviation.

For a simple explanation of the difference, see What is the difference between standard deviation and standard error?

For a more indepth explanation, perhaps Standard deviations and standard errors.