I wish to perform parallel analysis to determine how many factors I should extract from my maximum likelihood exploratory factor analysis. I have been referred to a program that calculates the eigenvalues for random data using Monte Carlo for principal component analysis. I am not doing principal component analysis, however. I am doing maximum likelihood exploratory factor analysis. I have been told that you can do it for any type of EFA, but I am uncertain. For example, a few of the macros I have seen require that you identify if you are using PCA or PAF. This clearly means that it matters to some extent.
Note that I have tried doing parallel analysis for PAF using the engine at http://ires.ku.edu/~smishra/parallelengine.htm. Unfortunately, the results did not make much sense. Every eigenvalue in my data was greater than the eigenvalue from the website, which I believe meant I should extra 100+ factors.
Questions:
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Can I use the parallel analysis results designed to be used with PCA to determine how many factors I should extract from my maximum likelihood factor analysis?
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If not (I expect the answer to the above question is "no"), how can I do a parallel analysis to determine how many factors I should extract from my maximum likelihood exploratory factor analysis?
Best Answer
I do not have an original source, but it appears this topic is actually quite debated. Some argue that you can do parallel analysis from PCA eigenvalues when doing PAF/maximum likelihood EFA, while others suggest this is inappropriate.
B. P. O'Connor wrote the following in his macro for parallel analysis for PCA/PAF (people.ok.ubc.ca/brioconn/nfactors/nfactors.html):