Process capability indice (estimate cpm)

Description

Estimate "cpm" using the method described by Kerstin Vannman(2001).

Usage

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qcs.hat.cpm(object, limits = c(lsl = -3, usl = 3), target = NULL, mu = 0,
  std.dev = 1, nsigmas = 3, k0 = 1, alpha = 0.05, n = 50,
  contour = TRUE, ylim = NULL, ...)

Arguments

object

qcs object of type "qcs.xbar" or "qcs.one".

limits

A vector specifying the lower and upper specification limits.

target

A value specifying the target of the process. If is NULL, the target is set at the middle value bewteen specification limits.

mu

A value specifying the mean of data.

std.dev

A value specifying the within-group standard deviation.

nsigmas

A numeric value specifying the number of sigmas to use.

k0

A numeric value. If the capacity index exceeds the k value, then the process is capable.

alpha

The significance level (0.05 for default)

n

Size of the sample.

contour

Logical value indicating whether contour graph should be plotted.

ylim

The y limits of the plot.

...

Arguments to be passed to or from methods.

References

Montgomery, D.C. (1991) Introduction to Statistical Quality Control, 2nd ed, New York, John Wiley & Sons.
Vannman, K. (2001). A Graphical Method to Control Process Capability. Frontiers in Statistical Quality Control, No 6, Editors: H-J Lenz and P-TH Wilrich. Physica-Verlag, Heidelberg, 290-311.
Hubele and Vannman (2004). The E???ect of Pooled and Un-pooled Variance Estimators on Cpm When Using Subsamples. Journal Quality Technology, 36, 207-222.

Examples

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library(qcr)
data(pistonrings) 
xbar <- qcs.xbar(pistonrings[1:125,],plot = TRUE)
mu <-xbar$center
std.dev <-xbar$std.dev
LSL=73.99; USL=74.01
qcs.hat.cpm(limits = c(LSL,USL),
           mu = mu,std.dev = std.dev,ylim=c(0,1))
qcs.hat.cpm(object = xbar, limits = c(LSL,USL),ylim=c(0,1))

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