# Quality Control Statistics

### Description

Create an object of class 'qcs' to perform statistical quality control. This object may then be used to plot Shewhart charts, Multivariate Control Charts, and more.

### Usage

1 2 3 4 5 6 7 8 9 10 11 12 13 14 | ```
qcs(x, sample.index, sizes = NULL, type = c("xbar", "R", "S", "one", "p",
"np", "c", "u", "ewma", "cusum"), center = NULL, std.dev, conf.nsigma = 3,
limits = NULL, type.data = c("continuous", "atributte", "dependence"),
lambda = 0.2, decision.interval = 5, se.shift = 1)
qcs.continuous(x, sample.index, sizes = NULL, type = c("xbar", "R", "S",
"one"), center = NULL, std.dev, conf.nsigma = 3, limits = NULL)
qcs.atributte(x, sample.index = NULL, sizes = NULL, type = c("p", "np",
"c", "u"), center = NULL, conf.nsigma = 3, limits = NULL)
qcs.dependence(x, sample.index = NULL, sizes = NULL, type = c("ewma",
"cusum"), center = NULL, std.dev, nsigma = 3, lambda = 0.2,
decision.interval = 5, se.shift = 1)
``` |

### Arguments

`x` |
a vector containing observed data | ||||||||||||||||||||||||||||||

`sample.index` |
a scalar with the column number corresponding to the index of each group (sample). | ||||||||||||||||||||||||||||||

`sizes` |
a value or a vector of values specifying the sample sizes
associated with each group. For continuous data the sample sizes are obtained counting the non- | ||||||||||||||||||||||||||||||

`type` |
a character string specifying the group statistics to compute:
| ||||||||||||||||||||||||||||||

`center` |
a value specifying the center of group statistics or the ”target” value of the process. | ||||||||||||||||||||||||||||||

`std.dev` |
a value or an available method specifying the within-group standard deviation(s) of the process. Several methods are available for estimating the standard deviation in case of a continuous process variable. | ||||||||||||||||||||||||||||||

`conf.nsigma` |
a numeric value used to compute control limits, specifying the
number of standard deviations (if | ||||||||||||||||||||||||||||||

`limits` |
a two-value vector specifying control limits. | ||||||||||||||||||||||||||||||

`type.data` |
a string specifying el type de data. | ||||||||||||||||||||||||||||||

`lambda` |
the smoothing parameter | ||||||||||||||||||||||||||||||

`decision.interval` |
A numeric value specifying the number of standard errors of the summary statistics at which the cumulative sum is out of control. | ||||||||||||||||||||||||||||||

`se.shift` |
The amount of shift to detect in the process, measured in standard errors of the summary statistics. | ||||||||||||||||||||||||||||||

`nsigma` |
a numeric value used to compute control limits, specifying the number of standard deviations. |

### Value

Returns an object of class 'qcs'.

### References

Montgomery, D.C. (2000) *Introduction to Statistical
Quality Control*, 4th ed. New York: John Wiley & Sons.

Wetherill, G.B.
and Brown, D.W. (1991) *Statistical Process Control*. New York:
Chapman & Hall.