Post by firstname.lastname@example.org
I'm trying to do a factor analysis on a questionnaire with 63 questions. Andy Field's SPSS book says the determinant of the correlation matrix shouldn't be less than .00001. Mine is 5.125E-16, and that's after removing the 8 questions with the highest intercorrelations (R>.7). Any suggestions? Thank you in advance.
I never noticed that criterion anywhere, but my (many)
FAs were almost always performed on smaller sets of items,
any my items usually were Likert-type scale items. What do
you have as your questionnaire items, more specifically?
You do not have 10 or 20 times the number of cases as
your number of items. That's a frequent recommentation.
But that advice is based on items with not-large correlations,
where that large of an N is needed to get a robust structure
If you do have Likert-type items, correlations of
more than 0.70 would be extremely large, since that
is about the maximum they should yield from their
What does your attempt at FA give you? Reasonable
factors? Are the estimated communalities reasonable
estimates for the item reliabilities?
- In case of small N (which yours /might/ be), I have
done FA with fixed estimates of reliability for the diagonal.
Hope this help.