Standard error

The standard error, sometimes abbreviated as ${\displaystyle SE}$,^[1] is the standard deviation of the sampling distribution of a statistic.^[2] The term may also be used for an estimate (good guess) of that standard deviation taken from a sample of the whole group.

The average of some part of a group (called a sample) is the usual way to estimate the average for the whole group. It is often too hard or too costly to measure the whole group. But if a different sample is measured, it will have an average that is a little bit different from the first sample. The standard error of the mean is a way to know how close the average of the sample is to the average of the whole group. It is a way of knowing how sure one can be about the average from the sample.

In real measurements, the true value of the standard deviation of the mean for the whole group is usually not known. So the term standard error is often used to mean a close guess to the true number for the whole group. The more measurements there are in a sample, the closer the guess will be to the true number for the whole group.

1. ↑ "List of Probability and Statistics Symbols". Math Vault. 2020-04-26. Retrieved 2020-09-12.
2. ↑ Everitt B.S. 2003. The Cambridge Dictionary of Statistics, CUP. ISBN 0-521-81099-X