Linnet K
Clin Chem. 1987 Mar;33(3):381-6.
In two-stage transformation systems for normalization of reference distributions, the asymmetry is first corrected, and any deviation of kurtosis is then adjusted. The simulation studies reported here show that these systems have previously been assessed too optimistically because the sample variation of the transformation parameters was neglected. Applying a goodness-of-fit test to transformed values shows that one should accept gaussianity only for p-values greater than 0.15 instead of those greater than 0.05. Further, the calculated 90% confidence intervals of reference limits should be expanded by 25%. When the correct level of significance is used, only real reference distributions that deviate moderately from the gaussian form are normalized. Calculation of confidence intervals demonstrated that 50 to 450 subjects are needed for a precise parametric estimation of the 95% reference interval. For the nonparametric approach, 125 to 700 reference subjects are necessary. The larger sample sizes are needed when distributions show pronounced skewness.
在用于参考分布标准化的两阶段转换系统中，首先校正不对称性，然后调整峰度的任何偏差。此处报告的模拟研究表明，这些系统此前被评估得过于乐观，因为转换参数的样本变异性被忽略了。对转换后的值进行拟合优度检验表明，只有当p值大于0.15而非大于0.05时，才应接受数据呈高斯分布这一假设。此外，计算出的参考限值的90%置信区间应扩大25%。当使用正确的显著性水平时，只有那些与高斯形式有适度偏差的实际参考分布才会被标准化。置信区间的计算表明，精确参数估计95%参考区间需要50至450名受试者。对于非参数方法，需要125至700名参考受试者。当分布呈现明显偏态时，需要更大的样本量。
