Re: Positive loadings with PROMAX, negative with OBLIMIN

Posted by Art Kendall on Nov 08, 2013; 11:45pm
URL: http://spssx-discussion.165.s1.nabble.com/Positive-loadings-with-PROMAX-negative-with-OBLIMIN-tp5722956p5722957.html

In any case, there is no intrinsic meaning to the direction that the artificial dimension takes.  E.g., for one set of cases to another the signs may all be flipped.

On 11/8/2013 5:45 PM, Bruce Weaver [via SPSSX Discussion] wrote:

Here's another little factor analysis mystery I stumbled across.  I'm using the data file available on this UCLA webpage:  http://www.ats.ucla.edu/stat/spss/output/factor1.htm.  Here's my syntax, with my question at the end.


NEW FILE.
DATASET CLOSE all.

GET FILE='C:\bw\SPSS\data\UCLA\M255.SAV'.

DESCRIPTIVES item13 to item24.

factor
 /variables item13 to item24
 /print initial extraction rotation fscore
 /format blank(.30)
 /criteria factors(3) iterate(100)
 /extraction paf
 /rotation promax
 /method = correlation.

* Factor 3 loadings (from Pattern Matrix) are:  0.781 and 0.821.
* This matches results shown in one analysis on the UCLA web-page.

factor
 /variables item13 to item24
 /print initial extraction rotation fscore
 /format blank(.30)
 /criteria factors(3) iterate(100)
 /extraction paf
 /rotation oblimin
 /method = correlation.

* Factor 3 loadings (from Pattern Matrix) are:  -0.778 and -0.814.

* Q. Why does the sign change when I switch from PROMAX to OBLIMIN? .


My apologies to the EFA experts out there if this is a well-known phenomenon.  (I'm a bit of a duffer when it comes to multivariate stuff, including EFA!)  

Cheers,
Bruce

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