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在人体正常值研究、环境监测等多项工作中,限于测试手段的敏感度(灵敏度),而在一组样品中,可能出现某些小于敏感度值(或检出下限)以下的“零”值个数,即“未检出”个数。它们是根据被测物实际总体,分布在从真“零”值到该敏感度值之间。此时,被测物实际总体多数是按正态分布、二项分布、偏态分布、L形分布的频数分布规律。按正偏态分布或正L形分布的频数分布规律尤其多见。由于环境污染的普遍性,在测定人体及环境中人工合成化学品时,得到真“零”值的个数,其数甚微;特别是当被测物是自然存在的化学元素时,其数极微。若完全以“零”值代替“未检出”值进行资料整理,甚不合理。为使结论更为真实;特别是为了能利用对数进行统计运算(lgO无意义,无法运
In many studies such as normal human value research and environmental monitoring, the sensitivity (sensitivity) of the test method is limited, while in a group of samples, there may be some “zeroes” below the sensitivity value (or lower detection limit). The number of values, that is, the number of “undetected”. They are based on the actual population of the measured object and are distributed from the true “zero” value to the sensitivity value. At this point, the actual overall majority of the measured object is the frequency distribution law of normal distribution, binomial distribution, skewed distribution, and L-shaped distribution. The frequency distribution of positively skewed distribution or positive L-shaped distribution is especially prevalent. Due to the universality of environmental pollution, the number of true “zero” values is measured when measuring synthetic chemicals in the human body and the environment. The number is small; especially when the analyte is a naturally occurring chemical element, Very slight. It would be unreasonable to completely sort the data with “zero” values instead of “undetected” values. In order to make the conclusion more true; in particular, in order to be able to use the logarithm for statistical operations (lgO meaningless, can not be shipped