The Cox Hazard proportionality model has a very significant feature called proportionality assumption. There are numerous ways through which we can verify that a particular model fulfills the proportionality model. However, in this case, we will examine proportionality by incorporating time-dependent covariates, such as vcr and temp in the stocx command. Here, predictors as well as time are the interactions of time-dependent covariates. In the present case, interaction is used along with log because generally, this function is used more frequently, yet apart from this, one can use any other function. Note that if a time-dependent covariate is important, then it disobeys the proportionality assumption of that predictor. To summarize, we can say that all time-dependent variables support the proportionality assumption hazard:

Stcox age metfordrug j.med j.sests ccs.age j.sests nmohrr vmcr

(age metfordrug medicinet ssets) temp(lmlnn(_tnt))

failure _d:  censor
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