Measure of the dispersion of the possible differences between samples of two populations, usually the difference between the means of the samples.
A measure of variation of a population of means.
The extent to which the means of several different samples would vary if they were taken repeatedly from the same population. Differences between means are said to have statistical significance when they are greater than twice the standard error of those means, since the probability of this difference or a larger one occurring by chance is less than 5%.
A measure of variability that could be expected of a statistical constant following the taking of random samples of a given size in a particular set of observations. An important standard error is that of the difference between the means of two samples.