Ullah M I, Cuddihy V, Saunders K B, Addis G J
Thorax. 1983 Feb;38(2):113-8. doi: 10.1136/thx.38.2.113.
We have collected peak expiratory flow rates, one-second forced expiratory volumes, and forced vital capacities in sets of 10 or 20 values at one-minute intervals from 30 normal, 49 asthmatic, and 26 bronchitic subjects. Analysis shows that the derivatives are compatible with a normal distribution of the values in the sets, so that the true value is best represented by the arithmetic mean of all valid attempts. One-third of all subjects showed skewness in one or more indices but these were equally divided between positive and negative directions. There is no sign of the dominant negative skewness that would result if the true value was indeed a maximum, which could be approached or equalled but never exceeded. There is no sign that repetition worsens performance. Seventy-two subjects showed no regression in any index and those of the remainder who deteriorated were balanced by equal numbers in all categories who improved. There is a significant tendency for both the highest and the lowest values to occur in the earlier part of any series. Probability theory suggests that this is a statistical phenomenon. The best estimate of the true value of these indices is probably the mean of as many observations as can be conveniently obtained and the data can be treated statistically as if they were a sample from a normally distributed population.
我们收集了30名正常受试者、49名哮喘患者和26名支气管炎患者的呼气峰值流速、一秒用力呼气量和用力肺活量，每组10个或20个数值，每隔一分钟采集一次。分析表明，这些数据的导数与各组数值的正态分布相符，因此真实值最好用所有有效测量值的算术平均值来表示。三分之一的受试者在一个或多个指标上呈现偏态，但正负方向的偏态数量相等。没有迹象表明如果真实值确实是最大值会出现明显的负偏态，即真实值可以接近或等于但永远不会超过最大值。没有迹象表明重复测量会使测量结果变差。72名受试者在任何指标上都没有出现下降，其余受试者中测量结果变差的人数与所有类别中测量结果改善的人数相等，达到了平衡。在任何一组测量中，最高值和最低值都有显著的出现在序列较早部分的趋势。概率论表明这是一种统计现象。这些指标真实值的最佳估计可能是尽可能方便地获得的多个观测值的平均值，并且这些数据在统计上可以当作来自正态分布总体的样本进行处理。
