This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Predictive values of a screening test depends on 
Select and explain. 
A. Prevalence, B. Sensitivity, C. Health worker, D. None of the above
A: Prevalence
Answer: A: Prevalence 
Explanation: In addition to sensitivity and specificity, the performance of a screening test is measured by its predictive value which reflects the diagnostic power of the test.The predictive accuracy depends upon sensitivity, specificity and disease prevalence.The more prevalent a disease is in a given population, the more accurate will be the predictive value of a positive screening test.Park 23e pg: 140