Sample Variance (Course 4)

[J-Man]

This is a really silly question. When an exam question says "sample variance", do they mean divide by n or n-1? I've seen it both ways. In fact, in the ASM manual, problem 2.7, the solution uses "divide by n". But at the very beginning of Lesson 3, it is defined as "divide by n-1".

Any help appreciated! Thanks.

[Bama Gambler]

for sample variance divided by n-1 (so that sample variance is an unbiased estimator of the true vairance)

Bama Gambler

[Abraham Weishaus]

On the original CAS exam, the line about "sample variance" wasn't there. Instead, they said to do the problem according to Hogg and Klugman (a textbook from the previous syllabus). I probably should have omitted the line about assuming the sample mean and variance. Exam questions often do not give you a clear cut method for solving a problem, since they want to test your reasoning. In this problem, the answer choice ranges are wide enough so that you would get the same answer choice whether you used the sample or the population variance.

[J-Man]

Dr. Weishaus, thanks!