Summary

Using Cox regression, you have found a suitable model for the time to churn. The use of separate blocks for fitting the model has allowed you to guarantee that Customer category would be in the final model, while still taking advantage of the stepwise techniques for choosing the other variables in the model.

To create this model, you included Customer category in the second block. Alternatively, the addition of Customer category to the model could have taken place in the first block, and the stepwise methods to choose the other variables in the second block. As it turns out, the final model is the same in this case, but that may not always be so. Thus, it is important to consider block order as well as block contents.