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: Dental
[{'content': 'What kind of sampling should be done when there is a small group of patients, easily available? \nSelect and explain. \nA. Random sampling, B. Multiphase sampling, C. Multistage sampling, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Random sampling (simple random sampling)\n- It is a technique whereby each sampling unit has the same probability of being selected.\xa0\n- Random sampling\xa0is done, when there is a small group of patients.\xa0\nMultiphase sampling:\xa0\n- This is used to take basic data from a large sample and details from a sub-sample.\nMultistage sampling\n- The first stage is to select the groups or clusters. Then, subsamples are taken in as many subsequent stages as necessary to obtain the desired sample size.\xa0\nEg:\xa0\n1st stage: Choice of states within countries.\xa0\n2nd stage: Choice of towns within each state.\n3rd stage: Choice of neighborhoods within each town.\nSoben Peter\xa0\nEssentials of preventive and community dentistry\xa0\n4th edition', 'role': 'assistant'}]