正确解释控制图7大规则！异常趋势如何调查！
7 Rules For Properly Interpreting Control Charts
正确解释控制图7大规则
By Mark Durivage, QualitySystems Compliance LLC
Control chartsbuild upon periodic inspections by plotting the process outputs and monitoringthe process for special cau variation or trends. Control charts aredecision-making tools that provide information for timely decisions concerningrecently produced products.'
控制图建立在定期检查的基础上，绘制过程输出和监控过程的特殊原因的变化或趋势。控制图是一种决策工具，它为有关最近生产的产品的及时决策提供信息。
Control chartscan be ud to identify sources of variation, both common and special cau.Common cau variation is the variation inherent in the process. Common cauvari
ation is also known as the noi of the process. A process with only commoncau variation is highly predictable. A process that has a significantinherent common cau variation may not be capable of producing products thatmeet predetermined specifications. Common cau variation is said to accountfor 80% of the variation in any process and is considered management’sresponsibility.
耐寒绿植
控制图可以用来识别变异的来源，包括固有和特殊的原因。固有原因变异是过程中固有的。固有原因变异也被称为过程噪声。只有固有原因变异的过程是高度可预测的。具有显著的固有原因变异的工艺可能不能生产出符合既定标准的产品。固有原因变异占任何过程中80%的变异，并被认为是管理层的责任。
Special cau variationis variation that is not inherent to the process. A process with special cauvariation is highly unpredictable. Special cau variation is said to accountfor 20% of the variation in any process and is considered the worker’sresponsibility.
特殊原因变异是指并非该过程固有的变异。具有特殊原因变异的过程是高度不可预测的。
特殊原因的变异占任何过程中变异的20%，并被认为是工人的责任。
Control chartscontain a centerline — usually the mathematical average of the samples plotted— and upper and lower statistical control limits that define the constraints ofcommon cau variation and performance data plotted over time.
控制图包含一条中心线——通常是样本的数学平均值——以及定义固有原因变化约束的统计控制上、下限和随时间绘制的性能数据。
There are twogeneral classifications of control charts: variables and attributes charts.Variables are things that can be measured. Attributes are things that can becounted. The type of data (variable or attribute) will dictate the appropriatetype of control chart required to monitor a process. Table 1 can be ud forcontrol chart lection.
控制图一般分为两类:变量图（计量型控制图）和属性图（计数型控制图）。变量是可以测量的东西。属性是可以计数的东西。数据的类型(变量或属性)将决定监控过程所需的控制图的适当类型。表1可用于控制图的选择。
Table 1: ControlChart Selection Guide
控制图选择指引
Selection of thecorrect type of control chart is important to ensure the underlying statisticalconcepts are appropriate for the feature or attribute being measured.
选择正确类型的控制图对于所用的确保底层统计概念适合于待测特征或属性十分重要。
A process issaid to be in control when the control chart does not indicate anyout-of-control condition and contains only common caus of variation. If thecommon cau variation is small, then a control chart can be ud to monitorthe process. If the common cau variation is too large, the process will needto be modified or improved to reduce the amount of inherent variation to anacceptable level.
当控制图没有提示任何失控的情况，只包含固有变异原因时，即表示一个过程受控。如果固有原因变异很小，则可以使用控制图来监控该过程。如果固有原因的变化太大，则需要对该过程进行整改或改进，以将固有变异减少到可接受的水平。
When a controlchart indicates an out-of-control condition (a point outside the control limitsor matching one or more of the criteria in the rules below), the assignablecaus of variation must be identified and eliminated.
当控制图表明一个失控的情况(一个超出控制限度的点或符合下面规则中的一个或多个标准)，必须识别和消除变化的原因。
The followingrules can be ud to properly interpret control charts:
以下规则可用于正确解释控制图：
∙Rule 1 – One point beyond the 3 σ control limit
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∙规则1 ——任何1点超出3 σ控制限
∙看动作猜词语Rule 2 – Eight or more points on one side of the centerline without crossing
支气管炎干咳∙规则2 ——连续8点或以上在中心线同一侧
打击手∙Rule 3 – Four out of five points in zone B or beyond
∙规则3 ——连续5点中有4点在B区或B区以上
勇往直前近义词∙Rule 4 – Six points or more in a row steadily increasing or decreasing
∙规则4 ——6个点或更多连续递增或递减
∙Rule 5 – Two out of three points in zone A
汉诺威王朝∙无用的我看见了天规则5 ——连续3点有2点位于A区
∙Rule 6 – 14 points in a row alternating up and down
