Functions to plot Shewhart c chart
stats.c.Rd
Statistics used in computing and drawing a Shewhart c chart.
Usage
stats.c(data, sizes)
sd.c(data, sizes, ...)
limits.c(center, std.dev, sizes, nsigmas = NULL, conf = NULL)
Arguments
- data
the observed data values
- center
sample/group center statistic.
- sizes
samples sizes.
- std.dev
within group standard deviation.
- nsigmas
a numeric value specifying the number of sigmas to use for computing control limits. It is ignored when the
conf
argument is provided.- conf
a numeric value in \((0,1)\) specifying the confidence level to use for computing control limits.
- ...
catches further ignored arguments.
Value
The function stats.c
returns a list with components statistics
and center
.
The function sd.c
returns std.dev
the standard deviation of the statistic charted.
The function limits.c
returns a matrix with lower and upper control limits.
References
Montgomery, D.C. (2013) Introduction to Statistical Quality Control, 7th ed. New York: John Wiley & Sons.
Wetherill, G.B. and Brown, D.W. (1991) Statistical Process Control. New York: Chapman & Hall.