[R] How to understand the plotting of the cox.zph function

Terry Therneau therneau at mayo.edu
Tue Sep 6 15:11:53 CEST 2011

Under the assumption of PH, the graph would be a horizontal line at y=
log(2.9) = coefficient of the model.  That is, a constant hazard ratio.

Your plot shows that there is no effect early (HR of 1) but there is an
impact later.

Terry T

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