The difference between formula_377 and formula_374 becomes negligibly small for large "n"s. In finite samples however, the motivation behind the use of formula_377 is that it is an unbiased estimator of the underlying parameter formula_6, whereas formula_374 is biased. Also, by the Lehmann–Scheffé theorem the estimator formula_377 is uniformly minimum variance unbiased (UMVU), which makes it the "best" estimator among all unbiased ones. However it can be shown that the biased estimator formula_374 is "better" than the formula_377 in terms of the mean squared error (MSE) criterion. In finite samples both formula_377 and formula_374 have scaled chi-squared distribution with degrees of freedom: