# Interpretation of Odds Ratios

##### New Member
I had a basic query regarding interpretation of Odds Ratio. This particular problem was sent to me by one of my colleagues. The risk factor association of different risk factors with pancreatic cancer was studied in a case control study.
The values are:

SITUATION 1:
Risk Factor Odds ratio (95% Confidence limits)
RF-A 2.5 ( 1.1 - 3.1 )
RF-B 1.4 ( 1.3 - 1.7 )

SITUATION 2:
Risk Factor Odds ratio 95% Confidence limits
RF-A 2.5 1.1 - 9.5
RF-B 1.4 1.1 - 1.7

I would be grateful if you could post a reply on what would be the correct
interpretation of the Odds Ratio in situations 1 and 2.

Regards.

Last edited:

##### New Member
Hi...

Is it the OR value that is more important, or the Confidence interval lower limit and range?

#### fed1

##### TS Contributor
Odds ratio is ratio of odds.

Odds( event ) = Pr(event)/Pr(not event).

OR = odds(event given condition one) / odds( event given conditon tow)

For you this means
OR = odds( p.cancer in group A)/ odds( p.cancer in groupB)

Odds ratio has many niftirific property that make scientist like it.

http://en.wikipedia.org/wiki/Odds_ratio

##### New Member
@fed1
Thanks for your reply. The A and B denote two different Risk Factors, not the case and control groups.

I have modified the original post to better clear this. The query is on the interpretation of the Odds Ratio of the two different risk factors in the two given situations. Thanks.

#### giordano

##### New Member
My two cents: both situation have the same impact but situation 1 is more accurate than 2.