Counts Control Chart

An example may help to illustrate the construction of control limits for counts data. We are inspecting 25 successive wafers, each containing 100 chips. Here the wafer is the inspection unit. The observed number of defects turn into chart. http://www.itl.nist.gov/div898/handbook/pmc/section3/pmc331.htm.

Simple Example

library(qcc)
## Package 'qcc' version 2.7
## Type 'citation("qcc")' for citing this R package in publications.
df = read.csv("D:/R/1.csv")
head(df)
##   Wafer Number
## 1     1     16
## 2     2     14
## 3     3     28
## 4     4     16
## 5     5     12
## 6     6     20
qcc(df$Number, type="xbar.one", data.name="Number of Wafer Defects")

## List of 11
##  $ call      : language qcc(data = df$Number, type = "xbar.one", data.name = "Number of Wafer Defects")
##  $ type      : chr "xbar.one"
##  $ data.name : chr "Number of Wafer Defects"
##  $ data      : int [1:25, 1] 16 14 28 16 12 20 10 12 10 17 ...
##   ..- attr(*, "dimnames")=List of 2
##  $ statistics: Named int [1:25] 16 14 28 16 12 20 10 12 10 17 ...
##   ..- attr(*, "names")= chr [1:25] "1" "2" "3" "4" ...
##  $ sizes     : int [1:25] 1 1 1 1 1 1 1 1 1 1 ...
##  $ center    : num 16
##  $ std.dev   : num 5.28
##  $ nsigmas   : num 3
##  $ limits    : num [1, 1:2] 0.153 31.847
##   ..- attr(*, "dimnames")=List of 2
##  $ violations:List of 2
##  - attr(*, "class")= chr "qcc"