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[[Image:WBR0792.jpg|500px]]
[[Image:WBR0792.jpg|500px]]
|Explanation=The negative predictive value is the probability that a person really doesn't have disease if a test result is negative. The calculation is shown below.
|Explanation=To test sensitivity and specificity of a certain test, results need to be compared to that of the gold standard for the detection of the studied disease or outcome. The negative predictive value is the probability that a person really doesn't have disease if a test result is negative. The calculation is shown below.




[[Image:Biostat.png|600px]]
[[Image:Biostat.png|600px]]
Educational Objective: Negative predictive value (NPV) = [True negative/(True negative + False negative)]
|AnswerA=82.75%
|AnswerA=82.75%
|AnswerAExp=This refers to the sensitivity.
|AnswerAExp=This refers to the sensitivity.

Revision as of 01:54, 31 October 2013

 
Author [[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Biostatistics/ Epidemiology
Sub Category SubCategory::Dermatology
Prompt [[Prompt::A company is testing a new diagnostic tool for the detection of squamous cell carcinoma of the skin and comparing the results to biopsy specimens validated by professional dermatopathologists. The results are shown below. What is the probability that a person really doesn't have squamous cell carcinoma if his test result comes back negative?


]]

Answer A AnswerA::82.75%
Answer A Explanation AnswerAExp::This refers to the sensitivity.
Answer B AnswerB::80%
Answer B Explanation AnswerBExp::This refers to the positive predictive value.
Answer C AnswerC::94.11%
Answer C Explanation AnswerCExp::This refers to the NPV.
Answer D AnswerD::93.02%
Answer D Explanation AnswerDExp::This refers to the specificity.
Answer E AnswerE::76.92%
Answer E Explanation AnswerEExp::This does not refer to any particular value.
Right Answer RightAnswer::C
Explanation [[Explanation::To test sensitivity and specificity of a certain test, results need to be compared to that of the gold standard for the detection of the studied disease or outcome. The negative predictive value is the probability that a person really doesn't have disease if a test result is negative. The calculation is shown below.


Educational Objective: Negative predictive value (NPV) = [True negative/(True negative + False negative)]
Educational Objective:
References: ]]

Approved Approved::No
Keyword WBRKeyword::Negative, WBRKeyword::predictive, WBRKeyword::value, WBRKeyword::negative predictive value
Linked Question Linked::
Order in Linked Questions LinkedOrder::