Statistics - explanations and formulas

Confidence Interval

A 95 percent confidence interval indicates that if the study were repeated 100 times, the study results would fall within this interval 95 times.  “a range of values within which we can be 95% sure that the true values lie.”  A narrow CI is good. A CI that spans 1.0 calls into question the validity of the result (because if repeated 95 times, sometimes the HR would be greater than 1.0)