Uniqueness calculation in EFA

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David
Posts: 30
Joined: Wed Jun 13, 2018 10:18 am

Uniqueness calculation in EFA

Post by David »

Hi, in a five factor EFA solution the uniqueness calculation seems a bit off, not sure why. Hand calc gives me a uniqueness of 0.66 for a promax rotated solution but the jamovi displayed value is 0.74. Hand calc of the unrotated solution is correct, so I'm not sure why rotated factor loadings don't add up to displayed uniqueness. Using jamovi 0.9.5.5.
David
ps omv attached
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Ravi
Posts: 194
Joined: Sat Jan 28, 2017 11:18 am

Re: Uniqueness calculation in EFA

Post by Ravi »

Hi David,
So by default we use "Minimal Residuals" as the factor extraction method (just like the R package "psych" that we use in the background). However, "factanal" uses maximum likelihood as the extraction method. If you change the extraction method to maximum likelihood, the uniqueness should be the same again.

Cheers,
Ravi
David
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Joined: Wed Jun 13, 2018 10:18 am

Re: Uniqueness calculation in EFA

Post by David »

Hi Ravi, maximum likelihood also gives 0.66 uniqueness for a five factor promax rotated solution (hand calc) - but the displayes uniqueness is 0.74 (jamovi 0.9.5.8)
David
Posts: 30
Joined: Wed Jun 13, 2018 10:18 am

Re: Uniqueness calculation in EFA

Post by David »

jamovi 0.9.5.8 ... not sure why the shades appeared!
David
Posts: 30
Joined: Wed Jun 13, 2018 10:18 am

Re: Uniqueness calculation in EFA

Post by David »

jmv syntax shows nFactors = 2 but five are extracted using parallel method...could this be something to do with it? See attached.
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Screenshot 2018-11-23 at 12.14.54.png
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David
Posts: 30
Joined: Wed Jun 13, 2018 10:18 am

Re: Uniqueness calculation in EFA

Post by David »

..answering my own question, NFactors = 2 or NFactors = 5 in jmv syntax doesn't change things...
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Ravi
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Re: Uniqueness calculation in EFA

Post by Ravi »

But it does match the R result you calculated using 'factanal' now right?
David
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Joined: Wed Jun 13, 2018 10:18 am

Re: Uniqueness calculation in EFA

Post by David »

Using factanal handcalc uniqueness = 0.66 but displayed = 0.74, just like in psych. Probably something happening that I don't understand...I had thought that rotated factor loading should still sum to same communality / uniqueness as unrotated?
David
Posts: 30
Joined: Wed Jun 13, 2018 10:18 am

Re: Uniqueness calculation in EFA

Post by David »

Further digging shows that with orthogonal rotation (varimax) factor loadings combine correctly to displayed uniqueness, but not for oblique rotation (promax). Extraction method doesn't seem to make a difference.
David
Posts: 30
Joined: Wed Jun 13, 2018 10:18 am

Re: Uniqueness calculation in EFA

Post by David »

aah, pattern vs structure matrix!! Sorry I'm a bit rusty on fa
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