Wolfgang, Since you seem to be doing this in the psych package, it would have been faster to directly ask the author (me). Luckily, I saw the question on R-Help.
The principal components step is being done on the correlation matrix, not on the raw data matrix, thus, it is not able to find scores. However, since you have the components solution, you also the scoring weights. Taking your analysis: > tetra <- tetrachoric (image_na, correct=TRUE) > t_matrix <- tetra$rho > pca.tetra <- principal(t_matrix, nfactors = 10, n.obs = nrow(image_na), > rotate="varimax", scores=FALSE) scores <- image_na %*% pca.tetra$weights Bill On Jan 18, 2012, at 4:27 AM, wolfgang wrote: > Haj > > i try to perform a principal component analysis by using a tetrachoric > correlation matrix as data input > > tetra <- tetrachoric (image_na, correct=TRUE) > t_matrix <- tetra$rho > pca.tetra <- principal(t_matrix, nfactors = 10, n.obs = nrow(image_na), > rotate="varimax", scores=TRUE) > > the problem i have is to compute the individual factor scores from the pca. > the code runs perfect if i do not ask for the scores > > if i ask for the scores i get an error message > "Error in scale(x.matrix): object 'x.matrix' not found" > > can somebody help me? > > cheers > wolfgang > > -- > View this message in context: > http://r.789695.n4.nabble.com/computing-scores-from-a-factor-analysis-tp4306234p4306234.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > William Revelle http://personality-project.org/revelle.html Professor http://personality-project.org Department of Psychology http://www.wcas.northwestern.edu/psych/ Northwestern University http://www.northwestern.edu/ Use R for psychology http://personality-project.org/r It is 5 minutes to midnight http://www.thebulletin.org ______________________________________________ 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.
