Last data update: 2014.03.03
R: Functions to plot Shewhart S chart
Functions to plot Shewhart S chart
Description
These functions are used to compute statistics required by the S chart.
Usage
stats.S(data, sizes)
sd.S(data, sizes, std.dev = c("UWAVE-SD", "MVLUE-SD", "RMSDF"))
limits.S(center, std.dev, sizes, conf)
Arguments
data
the observed data values
center
sample/group center statistic.
sizes
samples sizes. Optional
std.dev
within group standard deviation. Optional for sd.S
function, required for limits.S
. See sd.xbar
.
conf
a numeric value used to compute control limits, specifying the number of standard deviations (if conf
> 1) or the confidence level (if 0 < conf
< 1).
Value
The function stats.S
returns a list with components statistics
and center
.
The function sd.S
returns std.dev
the standard deviation of the statistic charted.
The function limits.S
returns a matrix with lower and upper control limits.
Author(s)
Luca Scrucca luca@stat.unipg.it
References
Montgomery, D.C. (2005) Introduction to Statistical Quality Control , 5th ed. New York: John Wiley & Sons.
Wetherill, G.B. and Brown, D.W. (1991) Statistical Process Control . New York: Chapman & Hall.
See Also
qcc
Results