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
[{'content': 'Positive predictive value is most affected by- \nSelect and explain. \nA. Prevalence, B. Sensitivity, C. Specificity, D. Relative risk', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref:Parks 25th edition pg.153 Postitive predictive value depends on prevalence. Note : PPV increases as prevalence increases. PPV decreases as prevalence decreases. But sensitivity and specificity is independent of prevalence.', 'role': 'assistant'}]