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Testing for rare conditions

All that glitters is not gold. —William Shakespeare

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Fig. 1: The PPV can be very low if prevalence is low.
Fig. 2: The effect of sensitivity (P) and specificity (B) on determining prevalence (A) based on the test’s positivity rate (Q).


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Correspondence to Martin Krzywinski.

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Altman, N., Krzywinski, M. Testing for rare conditions. Nat Methods 18, 224–225 (2021).

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