0

I'm trying to run discrete-time survival analysis using the survival package on R. My goal is to generate a graph that shows separate survival plot lines for each level of the "group" variable.

I tried to do this by using: cox <- coxph(Surv(timepoint,graduation)~lowincome + strata(group) + (1|districtID/schoolID/studentID), data=mydata)

But I receive an error message that says: Error in model.matrix.default(Terms2, mf, constrasts.arg = contrast.arg) : model frame and formula mismatch in model.matrix()

I'm not sure how to resolve this! I did see people who ran into similar errors on stackflow, but I can't figure out how to apply the solution to my dataset. My dataset includes 9 timepoints for each student ID, which are nested in school IDs, which are also nested in district IDs. This is a typical educational data structure (student-school-district).

I can provide a sample of my dataset, too, if that's helpful! Please advise how I could attach it.

Thank you.

programmingnewbie
  • 3
  • 3
  • Hi! Indeed, a sample of your data would be very helpful to reproduce your error and finding a solution. You can find guidelines on how to share sample data in the following link https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example – Juan Bosco Apr 18 '22 at 18:34

0 Answers0