Hi Team,
I was using your "psych" package for factor analysis and was also comparing
the results with SAS results. I have some suggestions and/or confusions
regarding the fa() function in the package:
- The fa() function *doesn't account for Heywood cases* (communality
greater than 1) and never ever throws out any error related to that which
other softwares do. This is a serious and common issue in iterative factor
analysis and hence should have been accounted for.
- The fa() function doesn't provide "equamax" rotation in its rotation
list and still if you specify "*rotation=equamax*", it will run without
throwing out any error and even mentioning in the result that "equamax" has
been applied. But I have thoroughly compared results from "
*rotation=none*" and "*rotation=equamax*" options and they are exactly
same. *That means fa() is not doing the rotation at all and yet telling
that it is doing that!!* I have even mentioned "*rotation=crap*" option
just to check and surprisingly it ran(without any error) with the result
showing:
*Factor Analysis using method = gls*
* Call: fa(r = cor_mat, nfactors = 4, n.obs = 69576, rotate =
"crap", fm = "gls")*
I hope you understand the severity of this bug and hence
request you to correct this.
- To my sense, there might be some problem with "fm=ml" and "fm=pa"
options since the convergence issue should be with MLE method and not PA
method but while running factor analysis with PA, I am getting the
following warning:
*maximum iteration exceeded*
* The estimated weights for the factor scores are probably
incorrect. Try a different factor extraction method.*
If I compare the results of R and SAS,* I am getting
convergence error for MLE in SAS whereas I am getting the same error for PA
in R *!! I am not being able to understand this mismatch.
- If I call the *loading matrix like efa_pa$loadings, the matrix shown
has many blank cells whereas the final result showing the loadings doesn't
have so* !!
*Loadings:*
* PA1 PA2 PA3 PA4 *
*Var1 0.401 -0.243*
*Var2 0.336 -0.104 0.710*
*Var3 0.624 0.123 0.170 *
- Could you please explain* what the "com" column means* in the output:?
* PA1 PA3 PA2 PA4 h2 u2 com*
*Var1 0.44 0.14 -0.03 -0.10 0.22665 0.773 1.3*
*Var2 0.08 0.11 0.02 0.78 0.62951 0.370 1.1*
*Var3 0.62 0.12 0.15 0.14 0.43578 0.564 1.3*
- Request you to add option for *"equamax" rotation* also if possible.
I have come across the above issues until now. Please do correct me if I am
wrong.
Awaiting your revert which would clear out my confusions,
Thanks for your valuable time,
Sagnik
--
Regards,
*SAGNIK CHAKRAVARTY*
*Mob:* +919972865435
*Email:* sagnik.st...@gmail.com
sagnik....@gmail.com
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
