Ehrmeyer S S, Laessig R H
Clin Chem. 1987 Jun;33(6):788-91.
The most common evaluation criterion used by regulatory and voluntary interlaboratory proficiency testing (PT) programs to judge the quality of chemistry results is based on the group mean +/- 2.0 standard deviations (SD), the 1(2)s rule. The mean and SD are those of the selected PT population. Through computer simulations we have quantified, for the first time, the ability of the 1(2)s criterion to detect "acceptable" as well as substandard ("unacceptable") intralaboratory performance by PT. We found that the 1(2)s rule correctly identifies "acceptable" performance--i.e., low intralaboratory coefficient of variation (CV) values and small bias values--greater than 90% of the time. However, this criterion fails to detect laboratories with "unacceptable" bias and (or) CV at least 23% of the time. The high failure rate of the 1(2)s rule raises serious questions about its appropriateness for use by PT programs.
监管机构和自愿性实验室间能力验证（PT）计划用于评判化学检测结果质量的最常用评估标准是基于组均值±2.0标准差（SD），即1(2)s规则。均值和标准差是所选PT群体的均值和标准差。通过计算机模拟，我们首次量化了1(2)s标准检测PT中“可接受”以及低于标准（“不可接受”）的实验室内部性能的能力。我们发现，1(2)s规则能在超过90%的时间里正确识别“可接受”的性能，即实验室内部变异系数（CV）值较低且偏差值较小。然而，该标准至少有23%的时间无法检测出存在“不可接受”偏差和（或）CV的实验室。1(2)s规则的高失败率引发了对其是否适用于PT计划的严重质疑。
