I am running a regression with one categorical predictor (Group
), one categorical covariate (Sex
), and two continuous covariates on R. Once I use the model.check
function, this error comes up:
Error in `contrasts<-`(`*tmp*`, value = contr.funs[1 + isOF[nn]]) :
contrasts can be applied only to factors with 2 or more levels
I have looked at a lot of the discussion boards here, and I have reviewed my data countless times. My Group
and Sex
variables are entered as factors with three and two levels, respectively. I checked for missing data, I checked to see if there were any errors in group names, but nothing. I am not sure what to do here. Any help would be greatly appreciated.