sample variance

This is a practice question I came across when dong some goodness of fit test examples.A company sells cloths by mail order.The size of clothes is defined by hip size; thus the height of customers of a particular customer may vary considerably. Data set of heights sent in by customers of size 18...

Several texts say that the mean of all values of an unbiased estimator is equal to the parameter it is estimating. They also say that the sample variance using Bessel's correction is an unbiased estimator of the population variance. Here's what I'm confused about: Consider a population...