I have been thinking about this for a long time. What are the possible variations of the mean in statistics? Is this the same as variance?
Each of the S samples produces a different sample mean. One way to portray the sampling variance of the mean appears on the right of the figure. This is the sampling distribution of the mean, a plotting of the frequency of specific different values of the sample mean (the x axis is the value of a sample mean and the y axis is the number of samples with that value among the S different samples). The dispersion of this distribution is the measure of sampling variance normally employed. If the dispersion of the distribution on the right is small, the sampling variance is low. (Sampling variance is zero only in populations with constant values on the variable of interest.)