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Visual design of diagnostics

Q: Are these curves parallel?

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?

A: Um. I’m not sure that helped. Still a definite maybe

Q: Is this curve horizontal?

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?