Suggested answer to exercise: survival after retirement, 3

Question 3. What is a log rank test and what can we conclude from this one?

Suggested answer

A log rank test is used to compare two survival curves. It uses data from all subjects, including those who are still surviving. It tests the null hypothesis that the risk of death in the two groups is the same at any given time of follow-up.

The P value is 0.09. This is larger than the conventional cut-off point of 0.05, so we would regard this as not providing good evidence for a difference. However, we can think of P values between 0.05 and 0.1 as providing rather weak evidence for a difference, not enough on its own to draw any firm conclusion.

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Last updated: 31 July, 2009.

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