# Can you use proportions as a covariate in a Cox proportional hazards model?

In R's survival::coxph function, can I mix a covariate representing proportions (in the range 0.0-0.5) with an integer covariate (in the range 1-15), or should I transform the first one also to integers (0-50)?

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You can mix them. As in other forms of regression, changing the scale will change the parameter estimates, but only in the same way that changing height from meters to feet would change it.

The meaning of the resulting model will be the same.

But you have to keep track of what you've done to the variables.

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