[R] SEM modelling

Dear All,   I am trying to run a program using SEM and the input data is a covariance matrix (polychoric correlations). However I get an error message which says:      is.triangular(S) : (list) object cannot be coerced to 'double'   Do not know what the problem is. Have do

[R] polr

Dear All, I am trying to use the packadge polr () to analyse ordinal categorical data responses. Instead of using polr() directly, I have altered the script slightly (imposed a constraint to make all the parameters greater than or equal to zero) (see below), fit <- list(coefficients = exp(be

[R] Importing data

Hi, I'm trying to import categorical data from SPSS to R using the script: xxx <-spss.get("xxx.por", use.value.labels=TRUE) but unfortunately am getting an error message 'error reading portable-file dictionary'. I have successfully imported data in the past. What could be the problem with this