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I was shocked to see something called Attibutable Risk Percent or Etiologic Fraction in a USMLEWorld CK question.

I did not encounter such thing in Kaplan notes or in FA or in my medical school or in High yield biostatistics book that I read for the boards.

For those of you who wants to know what is it.

It's calculated as follows
Risk in exposed - Risk in unexposed / Risk in exposed
RR-1 / RR

It tells how much percentage of the disease in the exposed population can be really attributed to the risk factor in question.

Now my question is, for such a rare complicated biostatistics equation and concept. Are we really going to see such questions in the real USMLE exam! If the answer is yes, then probably I will stop reading :eek:

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No I don't think you'll see such questions

Yes, you are right. That question is available not only in UW CK bank but also in their Step 1 and Step 3 banks.

I think this is a low yield concept. I don't think that the NBME wants us to go that far when it comes to biostatistics. They just want us to know the basic concepts and how to derive from those basic concepts.

For example they expect you to know how measure the sensitivity and how to derive conclusions from that, like less false negatives or more true positive ...etc.

The attributable risk percent you mentioned is not something that you can derive from core concepts. You have to know the formula in order to answer it. Therefore, I don't think they will ask such questions in the real exam.

USMLEWorld and other commercial question makers usually try to "impress" us with difficult and new concepts but that does not mean that such kind of questions will actually be seen in the real exam.
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