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-approximation 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

Author

Daniela R. Recchia, Emanuel P. Barbosa

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 produced

#> List of 11
#>  $ call      : language qcc(data = l, type = "p", sizes = n2, center = 0, limits = c(-SIGMA_MULT,      SIGMA_MULT), title = "Standardized| __truncated__
#>  $ type      : chr "p"
#>  $ data.name : chr "l"
#>  $ data      : num [1:13, 1] 309 274 196 224 281 ...
#>   ..- attr(*, "dimnames")=List of 2
#>  $ statistics: Named num [1:13] 2.58 2.29 1.78 2.8 3.51 ...
#>   ..- 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"