Q: Are these curves parallel?
![](https://68.media.tumblr.com/c1f42936a6f17a19b5b856d750cbab55/tumblr_inline_ovw0lnMAF71s1hdxy_540.png)
A: I mean, probably not? They look like they might be getting closer together, but if those big steps mean more uncertainty…
Q: Ok, how about with confidence intervals. Now are they parallel?
![](https://68.media.tumblr.com/9a77d08b121d01cc0a82348be260e8c3/tumblr_inline_ovw0ng5wMs1s1hdxy_540.png)
A: Um. I’m not sure that helped. Still a definite maybe
Q: Is this curve horizontal?
![](https://68.media.tumblr.com/d9adbd25eb626f4904ff72710f042715/tumblr_inline_ovw0pgBEat1s1hdxy_540.png)
A: No. It slopes down. It crosses zero somewhere around 8 or 9 years.
Q: Why do some statistics packages still provide the first graph for assessing departures from proportional hazards, rather than the second?
A: Tradition? Or textbooks?