Re: Positive loadings with PROMAX, negative with OBLIMIN

Posted by Rich Ulrich on Nov 10, 2013; 5:39am
URL: http://spssx-discussion.165.s1.nabble.com/Positive-loadings-with-PROMAX-negative-with-OBLIMIN-tp5722956p5722969.html

Art,
Good points, entirely.

I suppose my recommendation suits for the step, "What does
the data analyst first present to the PI?"

The PI needs to be made aware that he can use either end of the scale.
What makes the best name to represent this dimension?  Reverse
the signs, if that gives you the better name for representing the scores.


Rich Ulrich

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Date: Sat, 9 Nov 2013 10:21:40 -0800
From: [hidden email]
Subject: Re: Positive loadings with PROMAX, negative with OBLIMIN
To: [hidden email]

The signs on the factor loading are completely arbitrary.

Rich's suggestions  are certainly good ways to go in many circumstances. 

When one wishes to interpret the factor solution and especially when one wants  to develop a scoring key, e.g., for values,  attitudes, or solutions that end up with Osgood' semantic differential dimensions, I would use semantic criteria to name and pick the direction according to what the underlying construct is interpreted to be.
I would reflect items so the resulting score would go from semantically negative to positive (left to right or down to up when graphing)

low  ... high
weak ... strong
no threat  ...  very threatening
undesirable ... desirable
quiet ... active
inexpensive ... expensive
rarely ... frequently
unfair ... fair
inefficient ... efficient


On 11/9/2013 11:33 AM, Rich Ulrich [via SPSSX Discussion] wrote:

[re-post, in case you did see the first.  Slightly re-worded.]
As everyone says, the  +/-  direction of the vector is wholly
arbitrary and irrelevant to the meaning. 
 
A method of solution results in a set of signs; a slight variation
in the method (or data) might readily result in reversed signs.

I remember a convention suggested for how-to-display solutions:
compare the sums of negative and positive loading-squared terms,
and switch all signs if the negatives are bigger.  That could be a
standard either for programming or for data presentation in reports.  
"Eyeballing" usually gives an easy answer for Varimax.

Oblique rotations give larger loadings in general.  Simplified
standards for eyeballing include, "Make the largest loading
positive" and "Make the majority of loadings positive."

I wonder, but not very much, how many computer programs implement
any of these rules of thumb.

--
Rich Ulrich

> Date: Sat, 9 Nov 2013 05:46:03 -0800
> From: [hidden email]
> Subject: Re: Positive loadings with PROMAX, negative with OBLIMIN
> To: [hidden email]
>
> Thanks to Art, David & Mike. That's helpful.
>
> ...