# Questions regarding cox regression

#### perhexilline

##### New Member
Hi all, just some questions regarding interpretation of cox regression, thanks for any time or help you can spare.

If the variable under investigation has a negative co-efficient (i.e -0.5), how would you interpret a hazard ratio of <1 (i.e HR = 0.765)? would there be an increased or decreased association with the event? If increased, would the amount increased be 76.5% or 23.5%?

Second, if the variable under investigation was higher in the group with events (i.e 0.5 vs 0.3 in the group without events), how would you interpret a hazard ratio of 1.9? Would you say a 0.5 unit of the variable under investigation was associated with a 90% increased risk of the event? or would you say a 0.2 increment of the unit of the variable was associated with a 90% increased risk of the event?

Thanks all

#### hlsmith

##### Not a robit
You exponeniate your coefficient, so if after that it is below 1 along with its confidence interval, then it is protective. Like exercise and heart disease. If it is a categorical variable you can flip the reference group and it should be greater than 1 and you interpret the other categorical group.