This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Screening for Disease, Subject name: Social & Preventive Medicine
[{'content': 'Numerator in calculating positive predictive value - \nSelect and explain. \nA. True positive, B. False positive, C. True negative, D. False negative', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., True positive Sensitivity =Number of true positive--------------------------------------------Number of true positives + Number of false negative Specificity =Number of true negatives--------------------------------------------Number of true negative + number of false positives. Positive predictive value = -True positive--------------------------True positive + False positive Negative predictive value =True negative--------------------------True negative + False negative", 'role': 'assistant'}]