Phase II X-bar Shewhart Control Chart

Builds the X-bar control chart for Phase II monitoring using reference limits obtained from a Phase I analysis. The Phase I estimates of x2bar (mean of means) and sigma (standard deviation) are required, typically obtained from cchart.Xbar1.

Usage

cchart.Xbar2(x, x2bar, sigma, sizes)

Arguments

x: Phase II data. Matrix or data frame with subgroups in rows.
x2bar: Mean of subgroup means from Phase I (center line).
sigma: Standard deviation from Phase I (for control limits).
sizes: Phase II subgroup size(s).

Value

Draws the X-bar control chart. Returns nothing.

Phase convention

Phase II --- tests new data against Phase I reference distribution.

References

Montgomery, D.C., (2009). "Introduction to Statistical Quality Control". Chapter 6. Wiley.

Author

Daniela R. Recchia, Emanuel P. Barbosa

Examples


data(pistonrings)
stat <- cchart.Xbar1(pistonrings[1:25, ], 5)

cchart.Xbar2(pistonrings[26:40, ], stat[[1]][1], stat[[1]][2], 5)

#> List of 11
#>  $ call      : language qcc(data = x, type = "xbar", center = x2bar, std.dev = sigma)
#>  $ type      : chr "xbar"
#>  $ 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] 74 74 74 74 74 ...
#>   ..- 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 74
#>  $ std.dev   : num 0.00979
#>  $ nsigmas   : num 3
#>  $ limits    : num [1, 1:2] 74 74
#>   ..- attr(*, "dimnames")=List of 2
#>  $ violations:List of 2
#>  - attr(*, "class")= chr "qcc"