In cleaning out my inbox, I came to this note, to which I had intended to reply long since. In case the references might be useful to someone, I include them now...
On Wed, 29 Jan 2003, Rich Ulrich wrote in part: > On Thu, 16 Jan 2003 20:35:02 GMT, Jerry Dallal > <[EMAIL PROTECTED]> wrote: > > > Dennis Roberts wrote: > > > > > Comments appreciated. > > > > I think that what you and Rich are struggling with is that there is > > a difference between an expected length and a given probability of > > not exceeding some length. If it's not, it's still an issue. > > After trying to figure what to post next, I have finally > concluded that nobody else knows how to figure that, either. > (a) I don't have a textbook reference on how to figure > the CI of a standard deviation; > (b) I don't remember where and when I learned it; and > (c) most of you folks don't know what I was talking about, > because you have never walked through the basic problem. .. after which Rich presented "an elementary lesson". Textbook references: Glass & Stanley, "Statistical Methods in Education and Psychology", Prentice-Hall, 1970. Section 14.6, Inferences about <ratio of variances> using independent samples, pp 303-306. Glass & Hopkins, "Statistical Methods in Education and Psychology", 2nd ed., Prentice-Hall, 1984. Section 13.6, Inferences about two independent variances, pp 262-265. Both texts show how to test the hypothesis that two independent variances are equal, and how to construct a confidence interval on the ratio between the variances. Glass & Stanley was almost the first text I taught from after I started teaching graduate school in 1969, and I'd always believed that this material was part of the underlying basic stuff that folks like me were s'posed to know. [ snip, Rich's excellent exposition on the topic ] Happy Thanksgiving, all! -- Don Burrill. ----------------------------------------------------------------------- Donald F. Burrill [EMAIL PROTECTED] 56 Sebbins Pond Drive, Bedford, NH 03110 (603) 626-0816 . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
