R control chart
This function builds a R control chart.
cchart.R(x, n, type = "norm", y = NULL)
Arguments
| x | The data to be plotted. |
|---|---|
| n | The sample size. |
| type | The type of R chart to be plotted. The options are "norm" (traditional Shewhart R chart) and "tukey" (exact R chart). If not specified, a Shewhart R chart will be plotted. |
| y | The data used in phase I to estimate the standard deviation. |
Value
Return a R control chart.
Details
The Shewhart R chart was designed for phase I (at this moment). The limits of the exact R chart are the alpha/2 and 1-alpha/2 quantiles of the R distribution that are calculated as estimated process sd times the quantiles of the relative range (W=R/sigma) distribution.
Examples
data(pistonrings) attach(pistonrings) cchart.R(pistonrings[1:25,], 5)cchart.R(pistonrings[26:40, ], 5, type = "tukey", pistonrings[1:25, ])#> List of 11 #> $ call : language qcc(data = x, type = "R", limits = c(qtukey(0.00135, n, Inf) * sd.R(y), qtukey(0.99865, n, Inf) * sd.R(y))) #> $ type : chr "R" #> $ data.name : chr "x" #> $ data : num [1:15, 1:5] 74 74 74 74 74 ... #> ..- attr(*, "dimnames")=List of 2 #> $ statistics: Named num [1:15] 0.044 0.025 0.015 0.019 0.017 ... #> ..- attr(*, "names")= chr [1:15] "26" "27" "28" "29" ... #> $ sizes : Named int [1:15] 5 5 5 5 5 5 5 5 5 5 ... #> ..- attr(*, "names")= chr [1:15] "26" "27" "28" "29" ... #> $ center : num 0.0245 #> $ std.dev : num 0.0105 #> $ nsigmas : num 3 #> $ limits : num [1, 1:2] 0.00388 0.05262 #> ..- attr(*, "dimnames")=List of 2 #> $ violations:List of 2 #> - attr(*, "class")= chr "qcc"
