If (we can assume) the population is normal, then the chi-square distribution can be used to test the sample variance (this is analogous to using the student's t for a test of the sample mean).
David's XLS: http://trtl.bz/011018-yt-sample-variance-xls
David's XLS: http://trtl.bz/011018-yt-sample-variance-xls
