[R] Psych package: why am I receiving "NA" for many of the factor scores?

[William Revelle]

Dear Elizabeth,

Factor scores in the fa function are found by multiplying the standardized data by the factor weights using matrix multiplication.  This will give scores only for subjects with complete data.

However, if you want, you can create them yourself by standardizing your data and then multiplying them by the weights:

mydata <- rProjectSurveyDataJustVariables

f4 <- fa(my.data,4)  #modify this to match your call
wts <- f4$wts
scaleddata <- scale(mydata)
scores <- apply(scaleddata,1,function(x) sum(x * wts,na.rm=TRUE))   

#this will work with complete data, and impute factor scores for those cases with incomplete data.  If the data are missing completely at random, this should give a reasonable answer.  However, if the missingness has some structure to it, the imputed scores will be biased.

This is a reasonable option to add to the fa function and I will do so.

A side note.  If you need help with a package, e.g., psych, you get faster responses by writing to the package author.  I just happened to be browsing R-help when your question came in.

Let me know if this solution works for you.

Bill



> On Jan 13, 2015, at 7:46 PM, Elizabeth Barrett-Cheetham <ebarrettcheetham at gmail.com> wrote:
> 
> 
> Hello R Psych package users,
> 
> Why am I receiving "NA" for many of the factor scores for individual
> observations? I'm assuming it is because there is quite a bit of missing
> data (denoted by NA). Are there any tricks in the psych package for getting
> a complete set of factor scores? 
> 
> My input is: 
> rProjectSurveyDataJustVariables = read.csv("R Project Survey Data Just
> Variables.csv", header = TRUE)
> solution <- fa(r = rProjectSurveyDataJustVariables, nfactors = 4,  rotate =
> "oblimin", fm = "ml", scores = "tenBerge", warnings = TRUE, oblique.scores =
> TRUE) 
> solution
> 
> Thank you.
> 
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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/
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