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
[{'content': 'The following can be used as a yardstick for the assessment of standards of therapy? \nSelect and explain. \nA. Specific death rate, B. Case fatality rate, C. Propotional moality rate, D. Survival rate', 'role': 'user'}, {'content': "Answer: D \nExplanation: ref: Park's 23rd edition pg 58 It is the propoion of survivors in a group (eg: patients) studied and followed over a period. the survival period is usually reckoned from the date of diagnosis or the sta of treatment. mostly applied in cancer studies.", 'role': 'assistant'}]