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ProcessControl

 NPControlLimits
 compute control limits for the NP chart

 Calling Sequence NPControlLimits(X, n, options)

Parameters

 X - data n - sample size options - (optional) equation(s) of the form option=value where option is one of confidencelevel or pbar; specify options for computing the control limits

Description

 • The NPControlLimits command computes the upper and lower control limits for the NP chart. Unless explicitly given, the standard deviation of the underlying quality characteristic is computed based on the data.
 • 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.
 • The second parameter n specifies the size of the individual samples. All samples are expected to be of size n.

Computation

 • 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.

Options

 The options argument can contain one or more of the following options.
 • confidencelevel=realcons -- This option specifies the required confidence level. The default value is 0.9973, corresponding to a 3 sigma confidence level.
 • pbar=deduce or realcons -- This option specifies the average fraction of nonconforming items per data sample.

Examples

 > $\mathrm{with}\left(\mathrm{ProcessControl}\right):$
 > ${\mathrm{infolevel}}_{\mathrm{ProcessControl}}≔1:$
 > $A≔\left[12,8,6,9,10,12,11,16,10,6,20,15,9,8,6,8,10,7,5,8,5,8,10,6,9\right]$
 ${A}{≔}\left[{12}{,}{8}{,}{6}{,}{9}{,}{10}{,}{12}{,}{11}{,}{16}{,}{10}{,}{6}{,}{20}{,}{15}{,}{9}{,}{8}{,}{6}{,}{8}{,}{10}{,}{7}{,}{5}{,}{8}{,}{5}{,}{8}{,}{10}{,}{6}{,}{9}\right]$ (1)
 > $\mathrm{NPControlLimits}\left(A,100\right)$
 $\left[{0.621857384815469}{,}{18.0981426151846}\right]$ (2)
 > $\mathrm{NPControlLimits}\left(A,100,\mathrm{confidencelevel}=0.95\right)$
 $\left[{3.65118507440451}{,}{15.0688149255955}\right]$ (3)

References

 Montgomery, Douglas C. Introduction to Statistical Quality Control. 2nd ed. New York: John Wiley & Sons, 1991.