Incongruence between test statistics and P values in medical papers.
Incongruence between test statistics and P values in medical papers.
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DOI：
10.1186/1471-2288-4-13
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发表时间：
2004-05-28
影响因子：
4
通讯作者：
Alcaraz, Carles
中科院分区：
文献类型：
--
作者：
Garcia-Berthou, Emili;Alcaraz, Carles
背景：给定观察检验统计量及其自由度，可以用大多数统计包计算观察P值。尚不清楚已发表的医学论文中检验统计量和P值在多大程度上是一致的。方法：我们对《自然》（2001）第409-412卷的所有论文和《英国医学杂志》（2001）第322-323卷的63篇论文的统计结果进行一致性检查。我们还测试了610个测试统计样本的最后一个数字的频率是否偏离均匀分布（即等概率数字）。结果：2001年发表在《Nature》和《BMJ》上的统计结果中，分别有11.6%（181篇中21篇）和11.1%（63篇中7篇）的统计结果不一致，主要原因可能是舍入错误、转录错误或排版错误。《自然》和《英国医学杂志》分别有38%和25%的论文出现了至少一个这样的错误。在12%的情况下，显著性水平可能会改变一个或多个数量级。统计数据的最后一位数字的频率偏离了均匀分布，并表明在舍入和报告中数字的偏好。结论：检验统计量和P值的不一致是统计实践普遍较差的另一个例子，即使在最著名的科学期刊中，论文的质量应该得到更多的控制和重视。
BACKGROUND: Given an observed test statistic and its degrees of freedom, one may compute the observed P value with most statistical packages. It is unknown to what extent test statistics and P values are congruent in published medical papers.METHODS: We checked the congruence of statistical results reported in all the papers of volumes 409-412 of Nature (2001) and a random sample of 63 results from volumes 322-323 of BMJ (2001). We also tested whether the frequencies of the last digit of a sample of 610 test statistics deviated from a uniform distribution (i.e., equally probable digits).RESULTS: 11.6% (21 of 181) and 11.1% (7 of 63) of the statistical results published in Nature and BMJ respectively during 2001 were incongruent, probably mostly due to rounding, transcription, or type-setting errors. At least one such error appeared in 38% and 25% of the papers of Nature and BMJ, respectively. In 12% of the cases, the significance level might change one or more orders of magnitude. The frequencies of the last digit of statistics deviated from the uniform distribution and suggested digit preference in rounding and reporting.CONCLUSIONS: This incongruence of test statistics and P values is another example that statistical practice is generally poor, even in the most renowned scientific journals, and that quality of papers should be more controlled and valued.