Would be very grateful for any help people can offer re: below problem.

I'm doing a study comparing actual vs predicted outcome in a cohort of patients.

I essentially have two data sets that I would like to compare from the same cohort. All of these patients underwent a medical procedure (for ease's sake lets say removal of their appendix). I have the data confirming their

*actual*outcome (in terms of months survival). There is also a grading/prognostic score that can be used to calculate their

*predicted*outcome based upon a number of factors. I therefore have data for the cohort with each individual's

*actual*vs

*predicted*survival in months.

I've been trying to find a way to find if these two sets of data correlate with each other. In practical terms, how well do actual and predicted survival correlate? If the pre-procedure score suggests they will have a poor outcome (low months survival), is this seen in their actual survival?

I've heard mention about doing correlation coefficient or R-squared test to assess this. Are these the most appropriate tests? If not, why not and is there a better test I could use instead?

Thank you!