DrVirgo
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For a screening for Hepatitis C:
Sensitivity: 95%
Specificity: 90%
Known People with Hepatitis C: 10%
NPV is approximately....?
A. 99%
B. 95%
C. 90%
D. 85%
E. 50%
F. 45%
Please explain.
Thanks. 
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| robin082006
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A
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| robin082006
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.....................disease.............non-disease................total
Positive..........9.5.......................9............................ .18.5
Negative.........0.5......................81............................8 1.5
Total...............10.......................90.......................... ..100
NPV=81/81.5=99%
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The Key to Succeed is Patience.
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| robin082006
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.....................disease.............non-disease................total
Positive..........9.5.......................9............................ .18.5
Negative.........0.5......................81............................8 1.5
Total...............10.......................90.......................... ..100
NPV=81/81.5=99%
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The Key to Succeed is Patience.
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| DrVirgo
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Excellent.
You are absolutely right.
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| OBO
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Please explain how did u get these values? [ i think i am so dumb to ask this!!!
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| smal
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just imagine a population of 100 coz everything is in percent ok
and u can proceede
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| DrVirgo
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yup, its good to use 100. You can use any number really, because its all percentages. If you are more comfortable using 200, or 500, or even 1000, as the total population, you will still get the same answer.
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