On 24 Nov 2000 15:50:11 -0800, [EMAIL PROTECTED] (Alex Yu)
wrote:
>
> I ran a SAS macro and output a tetrachoric correlation matrix of 236
> variables successfully. However, when I ran a factor analsyis using the
> matrix as the infile, it fails. Although I have specified 'corr' for
> _type_, SAS said that:
>
< snip, rest >
Okay, I can accept that someone might propose that tetrachoric
correlations will do a better job of representing relations (than the
ordinary Pearson). However, if you want testing, I think I recall
advice that you use the test on the Pearson, or have at least 4 times
the N.
Here are related questions. I don't care for the idea, much, of
trying to factor 236 variables. But if someone wants to do so, should
the rule of thumb that says "use 10 times the N as the number of
variables" be modified to read "use 40 times ...?" Some other
number?
And, will the eigen values all be non-negative?
(I suspect that the answer is No, and that you shouldn't worry about
them. But I wouldn't mind hearing for sure.)
--
Rich Ulrich, [EMAIL PROTECTED]
http://www.pitt.edu/~wpilib/index.html
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