This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': 'Which of the following is ideal to ensure similarity between experimental & control groups \nSelect and explain. \nA. Randomization, B. Stratified randomization, C. Matching, D. Cross over study', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Stratified randomization: Study population is ‘first stratified’ by each variable which is considered important, and then randomization is done to each treatment groups within each stratum.\n- Comparison groups become similar as possible as regards participant characteristics that might influence the response to the intervention\n- Equal numbers of participants with a characteristic thought to affect prognosis or response to the intervention will be allocated to each comparison group.\n- Stratification increase the likelihood that two groups will be more comparable.', 'role': 'assistant'}]