We want to look at a particular subset of patients, and our primary interest is: What is the difference between the accuracy of predictions by healthcare practitioners of an outcome compared to the actual 6-month outcome. The outcome is measured on a yes/no basis. (ie: will this patient die, yes or no). Each patient will have several different practitioners that have predicted an outcome (so there will be several predictions for each true outcome).

Let’s say we are estimating that, on average, 20% of practitioners will predict a worse outcome than is actually encountered, how would I calculate the power needed to show this outcome. Power of 0.8 as standard, and p<0.05 for significance. For the record, for this subset of patients 0.48 will be the proportion with the measured outcome of interest.

Also, what would the best statistical test be to compare predicted outcomes to actual outcomes?

Thank you so much for your help. I’m a much better clinician than a statistician so I am grateful for your input.