Hello: I'm trying to construct a biplot from the psych package. The underlying data frame looks just like sample.data, below. I turned it into a polychoric correlation matrix sample.cor, below, as it is derived from a series of Likert (ordinal) items. All are positive, I just used negative numbers in this dataset to get two separate factors. I created a PCA from sample.cor$rho, specifying that scores were to be kept via scores=TRUE, but the command, biplot.psych(sample.mod) returns the error message: Error in biplot.psych, Biplot requires factor/component scores. But it seems from the help documentation, that one really only has to use the command biplot(mod) to get the plot. Can someone please advise? Yours, Simon Kiss
#Sample data sample.data<-data.frame(var1=sample(c(0,0.33, 0.66, 1), size=100, replace=TRUE), var2=sample(c(0,0.33, 0.66, 1), size=100, replace=TRUE), var3=sample(c(0,-0.33, -0.66, -1), size=100, replace=TRUE), var4=sample(c(0,-0.33,-0.66,-1), size=100, replace=TRUE)) #Correlation Matrix sample.cor<-polychoric(sample.data, polycor=TRUE) #Principal Components Analysis sample.mod<-principal(sample.cor$rho, nfactors=2,scores=TRUE,covar=TRUE) #Draw Biplot biplot.psych(sample.mod) #error Error in biplot.psych(sample.mod) : Biplot requires factor/component scores: ______________________________________________ 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.
