Dear Statalisters,
I have a question on factor analysis, using the -polychoric- option because
I have 4 dummy variables:
I run this program:
polychoric Var1 Var2 Var3 Var4
matrix R = r(R)
factormat R, n(6926) ipf factor(1)
rotate, horst blanks(.3)
predict FACTORROTATE
This way, I created an index based on the first factor. I needed this
variable to be included as coviariate in my regression. My question is: how
do I defend the fact that I have used one single factor? According to the
initial choice of number of factors I get a different value in the
"proportion" of the variance accounted for by the factor.
I add that I am using Stata 10.
Thanks in advance for answering to this silly question,
Francesco.
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