Re: Positive loadings with PROMAX, negative with OBLIMIN

Posted by David Marso on Nov 09, 2013; 6:23am
URL: http://spssx-discussion.165.s1.nabble.com/Positive-loadings-with-PROMAX-negative-with-OBLIMIN-tp5722956p5722958.html

Bruce,
  Plot the loadings in a 3-d scatterplot.  The 3rd factor of the oblimin is simply 180 degrees (flipped) from the promax.  Sign of the loadings is not of importance WRT interpretation.  Do a simple scatter of the two solutions (3rd factor) and they are practically on a straight line (negative slope).  I OMS'd the factor and structure matrices and played around but the battery on my LT fizzled before I could wrangle the output.
I'll leave it to OP Bruce to drill down into that (best turn off the blank (.30) to explore this).  Now, IBM (I guess Jon Why isn't the pattern matrix available in the OMS tags?  Oversight?
- BTW, why are you the only IBMer that posts here with any regularity?  Back in the day a lot of SPSS staff participated.  The only person recently was D Dwyer who looked into my MATRIX issue (where are D.Nich.... and D.Math...).  Oh well, I guess IBM doesn't give a hoot about SPSSX-L -aside from you Jon)
Squeak!  
HTH, David

Art Kendall wrote

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.
       
     
      Art Kendall
Social Research Consultants
      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
     
     
       --
       
        Bruce Weaver
       
        [hidden email] 
       
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