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Topic: F-test for comparing variances?
Replies: 1   Last Post: Nov 9, 2006 5:20 PM

 Reef Fish Posts: 1,021 Registered: 8/4/06
Re: F-test for comparing variances?
Posted: Nov 9, 2006 5:20 PM

Richard Ulrich wrote:
>
> There is an interesting little point about F-distributions at the
> end...
>
> On 6 Nov 2006 19:42:57 -0800, "Reef Fish"
> <large_nassua_grouper@yahoo.com> wrote:

> > > I'm pretty sure that the "larger over the smaller" was the old
> > > convention. I stated that, and how to use it; and Art re-stated it.

> >
> > There is NO such convention. You should have read what I posted.

>
> Bob also writes his posts without reading the next sentence.

< numerous gratuitous and irrelevant comments by Richard Ulrich
snipped>
>
> [snip]
> [snip]

> >
> > > RU> For some extreme cases, that formula gives a value greater than
> > > RU> 1.0. To avoid that, or to use a computer program for it, you can
> > > RU> get the exact p-value and if it is greater than 0.50, subtract from
> > > RU> 1.0; then double it.

> >
> > And I asked the question: Probability greater than 1?

>
RU> SPSS used to provide the "F-ratio test for variances"
>
RU> - I was amazed when I first saw p-values reported as greater
RU> than 1.0, like "1.07".
>
Richard was now trying to blame SPSS for his OWN errors.

>
> From Google, < define:gratuitous >
>
> Definitions of gratuitous on the Web:
> - without cause; "a gratuitous insult"
> - complimentary: costing nothing; "complimentary tickets"; "free