I'm trying to fit a Cox model, but there is some problems. I have the following variables in the model.

- Group: 1, 2, ..., 9

- Sex: 1 female and 0 male

- Weight

- Age

The first thing that I did is split the variables Age and Weight in 4 different groups and check if the assumption of proportional hazards is met for each variable. I did the plot of log-log(S(t))xt

The plot below is from Groups

For all the four variables the proportional hazard assumption is violated (crossed curves). Then I check it with hypothesis test and run the model

From the `summary` of model, Sex, Weight, Age are not significant. Then the model just have groups as variables.

So I did

I don't understand well this output, Group7 have prorportional hazard alone? How Sex, Age have proportional hazards if the curves of plot crossed?

If one level of categorical variable not hold the proportional hazard assumption, then the categorical variable not met the assumption right?