Posted by
Art Kendall-2 on
Nov 15, 2006; 2:07pm
URL: http://spssx-discussion.165.s1.nabble.com/PCA-factor-score-uses-tp1072110p1072111.html
You can use the factor scores in any design role.
Think of the factor scores as z-scores. Mean of zero, SD of 1.
What interpretation did you give to the two factors? Are the factors
bipolar or unipolar?
If you have 2 groups of respondents, and the mean factor scores you
mention are for these groups, then group 1 is at one end of the scale
and group 2 is at the other. The direction of factors is completely
arbitrary.
When developing scales, it is traditional to calculate scale scores by
summing items, reflecting those items that have negative weights.
Since reliability, correlations etc. are not changed by dividing by a
constant, you might want to work with a mean of the items.
It is also possible that you would want to reflect one or both scales so
that the high end is meaningful, e.g., high scores mean more racism.
The choice of direction is usually made to make correlations, etc., with
other variables have less complex verbal explanations.
Art Kendall
Social Research Consultants
Fredric E. Rose wrote:
>I'm not entirely familiar with PCA and could use some help.
>
>I've used PCA w/varimax rotation to reduce 10 variables (answers to a racism
>attitudes questionnaire) down to 2 factors. I want to know if the
>calculated factor scores for each participant can then be used as a
>dependent variable in subsequent analyses, or whether I should simply
>combine the variables loading on the respective factors and use those? My
>problem is in interpreting the factor scores: Group 1 has a mean of -2.72
>and Group 2 has a mean of 2.68. These are significantly different, but I'm
>not sure what the means represent (the raw data are scores ranging from 1 to
>10, so there are no negatives).
>
>Thanks for any insight.
>
>Fred Rose
>
>
>
>