Modified population variance

Mada

New Member
#1
I don't understand the term "modified population variance" used in this pdf file:///C:/Users/marya/AppData/Local/Packages/Microsoft.MicrosoftEdge_8wekyb3d8bbwe/TempState/Downloads/RSbook_ch3%20(1).pdf. Is it related to the concept of unbiased estimator of the population variance?

Also, why do we say that the formula for the sampling error of the mean is the population variance over sample size. Given sampling without replacement from a finite population, the nominator is the average sample variance when sampling over all possible samples.