ProcessControl[PControlLimits] - compute control limits for the P chart
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Calling Sequence
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PControlLimits(X, n, options)
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Parameters
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X
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data
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n
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sample size
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options
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(optional) equation(s) of the form option=value where option is one of confidencelevel or pbar; specify options for computing the control limits
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Description
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The PControlLimits command computes the upper and lower control limits for the P chart. Unless explicitly given, the standard deviation of the underlying quality characteristic is computed based on the data.
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The first parameter X is a single data sample, given as a Vector or list. Each value represents the number of nonconforming items in the corresponding sample.
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The second parameter n specifies the size of the samples. It can be either a positive integer, in which case all samples are assumed to be of size n, or a list (or Vector) of positive integers. Each value represents the size of the corresponding sample.
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Computation
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All computations involving data are performed in floating-point; therefore, all data provided must have type realcons and all returned solutions are floating-point, even if the problem is specified with exact values.
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For more information about computation in the ProcessControl package, see the ProcessControl help page.
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Options
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The options argument can contain one or more of the following options.
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confidencelevel=realcons -- This option specifies the required confidence level. The default value is 0.9973, corresponding to a 3 sigma confidence level.
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pbar=deduce or realcons -- This option specifies the average fraction of nonconforming items per data sample.
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Examples
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References
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Montgomery, Douglas C. Introduction to Statistical Quality Control. 2nd ed. New York: John Wiley & Sons, 1991.
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