5. Why do they say that employees who retired at 55 and were still alive at 65 had significantly higher mortality than those who retired at 65, when no P value is given?
The difference is significant at the 0.05 level because the 95% confidence interval for the hazard ratio, which is 1.09 to 1.73, does not include 1.00. This is the value the hazard ratio for the population would have if the null hypothesis were true.
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