Calculating NNT:
ARR Example

•That is if 10% of the untreated patients had the disease and 3% of the treated patients had the disease, then the treatment helped 7% (=10%-3%) of the treated patients (which if left without treatment would still likely have the disease). So 0.07 would be the ARR.

•Hence ARR is the probability that treatment will reduce the risk of a given patient beyond baseline expectation.