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

[William Revelle]

Dear Elizabeth,
  A correction to my suggestion:
scaled <- scale(mydata)
wts <- f4$weights

scores <-t( apply(scaled,1,function(x) colSums(x*wts,na.rm=TRUE)))  #you need the colSums not the sum function

Also, your confusion in getting the NAs with missing data was due to a bug in the fa function in the way it just ignored the missing statement.

Thanks for catching that.  It is now fixed and should be on CRAN real soon.

Bill





> On Jan 14, 2015, at 9:39 AM, William Revelle <lists at revelle.net> wrote:
> 
> 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/
> Use R for psychology             http://personality-project.org/r
> It is 5 minutes to midnight	   http://www.thebulletin.org
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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