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| | The author's name is Christy Brookins. The favorite hobby for him and his children is to play lacross and he would never give it up. Distributing manufacturing is where her main income comes from. For a whilst I've been in Alaska but I will have to move in a year or two.<br><br>Visit my weblog ... psychic love readings ([http://kjhkkb.net/xe/notice/374835 kjhkkb.net]) |
| {{Infobox control chart
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| | name = np-chart
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| | proposer = [[Walter A. Shewhart]]
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| | subgroupsize = n > 1
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| | measurementtype = Number nonconforming per unit
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| | qualitycharacteristictype = [[Variable and attribute (research)|Attributes data]]
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| | distribution = [[Binomial distribution]]
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| | sizeofshift = ≥ 1.5σ
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| | meanchart = Np control chart.svg
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| | meancenter = <math>n \bar p = \frac {\sum_{i=1}^m \sum_{j=1}^n \begin{cases} 1 & \mbox{if }x_{ij}\mbox{ defective} \\ 0 & \mbox{otherwise} \end{cases}}{m}</math>
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| | meanlimits = <math>n \bar p \pm 3\sqrt{n \bar p(1- \bar p)}</math>
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| | meanstatistic = <math>n \bar p_i = \sum_{j=1}^n \begin{cases} 1 & \mbox{if }x_{ij}\mbox{ defective} \\ 0 & \mbox{otherwise} \end{cases}</math>
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| }}
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| In [[statistical process control|statistical quality control]], the '''np-chart''' is a type of [[control chart]] used to monitor the number of [[Nonconformity (quality)|nonconforming units]] in a [[Sample (statistics)|sample]]. It is an adaptation of the [[p-chart]] and used in situations where personnel find it easier to interpret process performance in terms of concrete numbers of units rather than the somewhat more abstract proportion.<ref>{{cite book | last = Montgomery | first = Douglas | title = Introduction to Statistical Quality Control | publisher = [[John Wiley & Sons]], Inc. | year = 2005 | location = [[Hoboken, New Jersey]] | pages = 279 | url = http://www.eas.asu.edu/~masmlab/montgomery/ | isbn = 978-0-471-65631-9 | oclc = 56729567}}</ref>
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| The np-chart differs from the p-chart in only the three following aspects:
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| #The control limits are <math>n\bar p \pm 3\sqrt{n\bar p(1-\bar p)}</math>, where n is the sample size and <math>\bar p</math> is the estimate of the long-term process mean established during control-chart setup.
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| #The number nonconforming (np), rather than the fraction nonconforming (p), is plotted against the control limits.
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| #The sample size, <math>n</math>, is constant.
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| ==See also==
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| *[[p-chart]]
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| ==References==
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| {{reflist}}
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| {{DEFAULTSORT:Np-Chart}}
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| [[Category:Quality control tools]]
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| [[Category:Statistical charts and diagrams]]
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Latest revision as of 13:23, 5 May 2014
The author's name is Christy Brookins. The favorite hobby for him and his children is to play lacross and he would never give it up. Distributing manufacturing is where her main income comes from. For a whilst I've been in Alaska but I will have to move in a year or two.
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