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How to Calculate RR, RRR, ARR, and NNT/NNH ?


Prof. Mary Ferrill explains how to calculate RR, RRR (Relative RIsk Reduction), ARR (Absolute Risk Reduction), and NNT/NNH.

She starts this video with a table about the exposure and outcome for treatments. We can use this to help us calculate the parameters in the example in this video.

After comprehending Prof. Mary’s explanation, you can try to calculate the example on your own. If you have any questions, please leave them below.

Besides, she provides two websites that can help us to calculate the RR, RRR, ARR and NNT/NNH, and then illustrates the differences. Remember to take the significant figure into account.

We can calculate them with the box method, and use websites to double check.

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Evidence-Based Medicine in Clinical Pharmacy Practice

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FutureLearn - Learning For Life

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