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Running Omega in R

Hi David

Thank you for your feedback
I didn?t realise you couldn?t implement omega on a single factor
This definitely makes sense the more I read on it

Thank you all very much for your time 


From: David L Carlson
Sent: Monday 16 January 2017 16:43
To: peter dalgaard; Rui Barradas
Cc: John Smith; r-help at r-project.org; revelle at northwestern.edu
Subject: RE: [R] Running Omega in R

I get an additional error message when I run your example so perhaps your version is not the current (1.6.12) one? 

Loading required namespace: GPArotation
Failed with error:  ?there is no package called ?GPArotation??
Error in omegah(m = m, nfactors = nfactors, fm = fm, key = key, flip = flip,  : 
  I am sorry, you need to have the  GPArotation package installed

Then I get a great deal of error output followed by the one you list. The first error is 

"Omega_h for 1 factor is not meaningful, just omega_t" (repeated 174 times). I'm copying the package maintainer as this seems like overkill.

Your problem is addressed in the first line of the manual page for omega:

"McDonald has proposed coefficient omega as an estimate of the general factor saturation of a test. One way to find omega is to do a factor analysis of the original data set, rotate the factors obliquely, do a Schmid Leiman transformation, and then find omega. "

You cannot rotate a single factor so you cannot compute omega.

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of peter dalgaard
Sent: Sunday, January 15, 2017 2:27 PM
To: Rui Barradas <ruipbarradas at sapo.pt>
Cc: John Smith <jSmith.Coursera at outlook.com>; r-help at r-project.org
Subject: Re: [R] Running Omega in R
...although publishing a package is not the same as issuing a blank cheque for free support, so you may want to dig a little deeper first. 

I'd check the documentation for whether the data are in the right format. In particular, can "m" be a data frame? If it wants a matrix, you probably need to give it one (m=as.matrix(construct) should do it).

-pd