Currently I am working on an analysis using the cox model. I have about 200 observations. I built a model based on the results of univariate analysis (also cox, with the best p-value results).
In the next step, I would like to validate such a model. What validation strategy is recommended for such a sample size?
I was very interested in the article - LINK - but I don’t know exactly how to do this validation based on the rms package.
PS - I am beginner in R