Assessing actual patient outcomes is difficult. Coming up with data is time consuming, expensive, and full of potential pit-falls. And then using medical statistics to understand those figures is even more tricky. When a new study is published, it usually compares the new treatment or medication to the previous best method, and thus the gains are often very modest. And then to complicate things even further, it often quotes the results as an ‘odds ratio’. This is a concept that is often poorly understood.