使用 rms 包中的 lrm() 和 validate() 时出现错误消息

Question

I am trying to use validate() from the rms package but get an error. More specifically, I fit an ordinal logistic model using lrm() and then assess my results with validate() .

Please find some code below:

library(data.table)
library(rms)

DT2 <- data.table(internal_model_rating_number = c(5,5,5,5,6,6,5,5,5,5),
                  ratio = c(2.0665194,1.2264998,1.0333628,0.6936382,-0.1883890,
                        -0.2349949,-0.5062086,-0.5204016,-0.4401635,-0.5824366))
lrm.model <- lrm(internal_model_rating_number ~ ratio, 
                 x = T,
                 y = T,
                 data = DT,
                 maxit = 1000)
validate(lrm.model, group=internal_model_rating_number, B=200, bw=T)

Note that the group argument when running the code for my actual data (not displayed) is necessary, because some categories of the target variable occur very rarely.

The piece of validate() code returns the error:

Error in predab.resample(fit, method = method, fit = lrmfit, measure = discrim,  : 
  object 'internal_model_rating_number' not found

Do you know how I can solve this error?

Answer 1

I think the data has to be specified before the grouping variable.

Try this validate(lrm.model, group = DT2$internal_model_rating_number, B=200, bw=T)

You also had a small typo (try data = DT2 instead of DT .)

If you don't want to specify the data again, you can use attach(DT2) and then run your model.

library(data.table)
library(rms)

DT2 <- data.table(internal_model_rating_number = c(5,5,5,5,6,6,5,5,5,5),
                  ratio = c(2.0665194,1.2264998,1.0333628,0.6936382,-0.1883890,
                            -0.2349949,-0.5062086,-0.5204016,-0.4401635,-0.5824366))

attach(DT2)

lrm.model <- lrm(internal_model_rating_number ~ ratio, 
                 x = T,
                 y = T,
                 data = DT2,
                 maxit = 1000)

validate(lrm.model, group = internal_model_rating_number, B=200, bw=T)

Once you're done, if you'd like to detach the data, use detach(DT2)