Derive a final Cox PH model. Stratify on polytomous factors that do not satisfy the PH assumption. Decide whether to categorize and stratify on continuous factors that may strongly violate PH. Remember that in this case you can still model the continuous factor to account for any residual regression after adjusting for strata intervals. Include an interaction between two predictors of your choosing. Interpret the parameters in the final model. Also interpret the final model by providing some predicted survival curves in which an important continuous predictor is on the x-axis, predicted survival is on the y-axis, separate curves are drawn for levels of another factor, and any other factors in the model are adjusted to specified constants or to the grand mean. The estimated survival probabilities should be computed at t = 730 days.