# Confidence interval for odds ratio only just containing 1 [duplicate]

If I have an odds ratio of 1.2 say between group A and group B but a confidence interval of (0.99,1.5) which only just about contains 1. Can I make the conclusion that there is no association between group A and group B?

• This really comes down to the issue in the post Why do statisticians say a non-significant result means “you can't reject the null” as opposed to accepting the null hypothesis? You can't know for sure that the odds ratio in the population as a whole is "really" one; even in your sample you did not find an odds ratio of one. But if that was a 95% confidence interval, then you did not find significant evidence (at the $\alpha=0.05$ level) to reject the null hypothesis that the population odds ratio is one. Dec 12, 2015 at 16:46
• In other words, you do not have strong evidence that the true odds ratio isn't one ... but that doesn't mean you know the true odds ratio is one, either. Dec 12, 2015 at 16:49
• Briefly: you may conclude that you have not been able to detect an association (at your desired level of confidence).
– whuber
Dec 12, 2015 at 17:11
• @Silverfish , yes I would never feel comfortable writing "accepting the null"! Certainly been drilled out of me since high school, I was just wondering how much the actual closeness of the confidence interval matter. Dec 12, 2015 at 17:17
• In terms of how much the "closeness" matters: if you did a 95% confidence interval and it only just included one, then the p-value would be only just above 0.05. (So if you'd tested at e.g. $\alpha = 0.1$ then the result might have been significant, i.e. the 90% confidence interval may not have included one.) Dec 12, 2015 at 17:20