Why this stance?
You could justify your choice on scientific or substantive grounds, if
you have any.
You could try other choices and show that 1 produces the best results --
if that's true -- or alternatively that the choice is immaterial -- if
that's true. Alternatively, trying other choices might indicate that the
choice of 1 is not a good idea.
P.S. -polychoric- is a command, not an option. It is also a user-written
command, so you should say where it comes from.
P.P.S. the whole notion of variance is perhaps a little suspect when the
originals are indicator variables.
Nick
[email protected]
Francesco Burchi
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.
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
