This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Screening, Subject name: Social & Preventive Medicine
Most number of false positives by a screening test is becuase of? 
Select and explain. 
A. High specificity, B. High sensitivity, C. High prevalence, D. Low prevalence
D: Low prevalence
Answer: D: Low prevalence 
Explanation: Ref :Parks 23rd edition pg 140. PPV decreases as prevalence decreases. As PPV decreases it means that TP is decreasing. This is accompanied by an increase in FP PPV =TP /(TP +FP)