This is for a PhD, research in psycholinguistics.

I have done logistic regression analyses where some chosen predictor predicts the likelihood of the event happening. That is my rudimentary summary of what I am doing. Let me quickly define my event and non-event. These consist of difference scores that have been made binary. So if a difference score was positive, I coded it as 1; if it was negative, I coded it as 0. In my study this difference is very important. 0 does not mean simply NOT 1. It actually means that my participants were doing something else entirely. Interpreting the odds ratio correctly is crucial.

I am getting several odds ratios less than 1. For example, 0.881. I am told that this means: For every one unit increase in the independent variable, there is an 11.9% decreased likelihood of the event happening. If this is correct, it only partially answers what I need to know.

My question, how much does this tell me about the likelihood of the non-event happening? And how can I calculate that? I've read up quite a bit online about calculating reciprocals (because the odds ratio is invertible) but I get stuck and confused every time. And my Andy Field textbook doesn't address this in the detail that I need.

I've tried to provide as much detail as I think you need but not so much that it is superfluous and boring. If you can at all help me understand this, I would really appreciate it.

MariaF.