R: Statistics used in computing and drawing the Hotelling T^2 chart for subgrouped data

stats.T2 {qcc}

R Documentation

Statistics used in computing and drawing the Hotelling T^2 chart for subgrouped data

Description

These functions are used to compute statistics required by the T^2 chart.

Usage

stats.T2(data, center = NULL, cov = NULL)

limits.T2(ngroups, size, nvars, conf)

Arguments

`data`	the observed data values
`center`	a vector of values to use for center of input variables.
`cov`	a matrix of values to use for the covariance matrix of input variables.
`ngroups`	number of groups
`size`	sample size
`nvars`	number of variables
`conf`	confidence level (0 < `conf` < 1)

Value

The function stats.T2 returns a list with components:

`statistics`	a vector of values for the T^2 statistic
`means`	a matrix of within group means for each variable
`center`	sample/group center statistic
`S`	covariance matrix
`control`	control limits
`prediction`	pred.limits

Author(s)

Luca Scrucca luca@stat.unipg.it

References

Mason, R.L. and Young, J.C. (2002) Multivariate Statistical Process Control with Industrial Applications, SIAM.
Montgomery, D.C. (2005) Introduction to Statistical Quality Control, 5th ed. New York: John Wiley & Sons.
Ryan, T. P. (2000), Statistical Methods for Quality Improvement, 2nd ed. New York: John Wiley & Sons, Inc.