Hi,
On 02/27/2013 02:57 AM, Frantisek Kluknavsky wrote:
are you sure that "buggy" and correct behavior are not confused here?
I do not know, but look at
http://en.wikipedia.org/wiki/Bias_of_an_estimator and search for
"usual definition of sample variance". If I understand it correctly,
the "buggy" formula was unbiased, while now it is biased again.
The biased estimate is 21.5/n = 4.2984. The unbiased estimate is
21.5/(n-1) = 5.373. Note, that neither is buggy; both estimators are
used and it's a matter of taste which one is preferred. One is unbiased,
but the other one is more efficient.
HTH,
Peter
