统计问题（29）：
当卫生当局引入了一个新的基于社区的疫苗推广团队时，MMR（麻疹、腮腺炎、风疹）疫苗的接种率在接下来的两年中有所提高。此项改变具有统计学意义，单侧检验 P< 0.01。
以下哪项（如果有）是正确的？
A.由于 P 值低，不太可能混淆
B.如果疫苗接种率随时间随机变化，出现这样或更好结果的概率将小于0.01
C.疫苗接种率的差异很重要
D.可以认为团队方法比旧方法更好
Question
When a health authority introduced a new community based vaccine promotion team, vaccination rates for the MMR (measles, mumps, rubella) vaccine improved over the next two years. The improvement was statistically significant, with a one sided P value of less than 0.01. Which of the following, if any, are true?
A. Confounding is unlikely because of the low P value
B. If the vaccination rates were varying randomly over time then the probability of a result like this or better would be less than 1 in 100
C. The difference in vaccination rates is likely to be important
D. The team approach can be recommended as better than the old approach
Answer
The P value assesses only the play of chance and gives no information about bias or confounding. The importance of the result depends on a clinical judgment of the effect of the absolute magnitude of the change in vaccination rates. This is not reported in the question and is only one component of the calculation of the P value, the others being sample size and standard deviation. The decision to recommend one approach over another should include several other considerations, such as benefit, harm, acceptability, and costs. Answer b is a fair representation of what the P value describes.
中文解释：
P 值仅评估偶然性，不提供有关偏见或混杂的信息。结果的重要性取决于针对疫苗接种率变化的绝对幅度造成的影响的临床判断。 这在问题中没有报告，只是 P 值计算的一个组成部分，其他是样本大小和标准偏差。推荐一种方法的决定应包括其他几个考虑因素，例如收益、危害、可接受性和成本。答案 b 是对 P 值所描述内容的公平表示。
所以答案是选择 B
