WBR0792
| 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)] |
| Approved | Approved::No |
| Keyword | WBRKeyword::Negative, WBRKeyword::predictive, WBRKeyword::value, WBRKeyword::negative predictive value |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
