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Natural process variation, sometimes just called process variation, is the statistical description of natural fluctuations in process outputs. == Equations == The following equations are used for an ''x''-bar-control chart: : : In the example, with ''n'' = 10 samples, the targeted mean, , and standard error of the mean, are: : : That is, independent 10-sample means should themselves have a standard deviation of 0.0316. It is natural that the means vary this much, for by the central limit theorem the means should have a normal distribution, regardless of the distribution of the samples themselves. The importance of knowing the natural process variation becomes clear when we apply statistical process control. In a stable process, the mean is on target; in the example, the target is the filling, set to 1 litre. The variation within the upper and lower control limits (UCL and LCL) is considered the natural variation of the process. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Natural process variation」の詳細全文を読む スポンサード リンク
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