p-chart

This function builds p-charts.

cchart.p(x1 = NULL, n1 = NULL, type = "norm", p1 = NULL, x2 = NULL,
  n2 = NULL, phat = NULL, p2 = NULL)

Arguments

x1	The phase I data that will be plotted (if it is a phase I chart).
n1	A value or a vector of values specifying the sample sizes associated with each group for the phase I data.
type	The type of p-chart to be plotted. The options are "norm" (traditional Shewhart p-chart), "CF" (Cornish Fisher p-chart) and "std" (standardized p-chart). If not specified, a Shewhart p-chart will be plotted.
p1	The data used to estimate the phat (x1 / n1).
x2	The phase II data that will be plotted in a phase II chart.
n2	A value or a vector of values specifying the sample sizes associated with each group for the phase II data.
phat	The estimate of p.
p2	The values corresponding to x2 / n2.

Value

Return a p-chart.

Details

For a phase I p-chart, n1 must be specified and either x1 or p1. For a phase II p-chart, n2 must be specified, plus x2 or p2 and either phat, x1 and n1, or p1 and n1. The Shewhart is based on normal-aprroximation and should be used only for large values of np or n*p (n*p > 6).

References

Montgomery, D.C.,(2008)."Introduction to Statistical Quality Control". Chapter 11. Wiley

Examples

data(binomdata)
attach(binomdata)
#> The following object is masked from package:base:
#> 
#>     pi
cchart.p(x1 = Di[1:12], n1 = ni[1:12])
cchart.p(x1 = Di[1:12], n1 = ni[1:12], type = "CF", x2 = Di[13:25], n2 = ni[13:25])
cchart.p(type = "std", p2 = Di[13:25], n2 = ni[13:25], phat = 0.1115833)
#> Warning: NaNs produzidos
#> List of 11
#>  $ call      : language qcc(data = std, type = "p", sizes = n2, center = 0, limits = c(-3, 3),      title = "Standardized p-chart (phase II)")
#>  $ type      : chr "p"
#>  $ data.name : chr "std"
#>  $ data      : num [1:13, 1] 37110 32935 21576 17927 22473 ...
#>   ..- attr(*, "dimnames")=List of 2
#>  $ statistics: Named num [1:13] 309 274 196 224 281 ...
#>   ..- attr(*, "names")= chr [1:13] "1" "2" "3" "4" ...
#>  $ sizes     : int [1:13] 120 120 110 80 80 80 90 100 100 100 ...
#>  $ center    : num 0
#>  $ std.dev   : num NaN
#>  $ nsigmas   : num 3
#>  $ limits    : num [1, 1:2] -3 3
#>   ..- attr(*, "dimnames")=List of 2
#>  $ violations:List of 2
#>  - attr(*, "class")= chr "qcc"