统计问题(28):关于均数和中位数,说法正确吗? 一家医院里患者中风后的平均住院时间为21天,中位数为12天,标准差为13天。那么对于这些信息,下面说法哪些是正确的?(多选) Question a) The typical length of stay was 21 days b) The mean length of stay may be affected by long stay patients c) As many patients stayed for fewer than 12 days as stayed longer than 12 days d) When comparing length of stay in this hospital with that in another hospital, survival methods would be preferable to a t test Answer The typical value is hard to define. It might be the most frequent length of stay, which would be the mode. But if there are a large number of values then the mode may be true for only a few people. The median value is sometimes used because it is in the middle of the rank order. In a skewed distribution such as this, the mean is a lot higher than the median, because of long stay patients, and few people may stay for close on 21 days. The mean is certainly not the typical value here. Answer c is one way of defining the median. Survival methods are ideallysuited to measuring “time to event.” The event in this case would be dischargefrom hospital. These methods do not require a near normal distribution ofvalues as is preferable when using a t test. 中文解释: 所以答案是选择 B,C,D |
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