Function which implements rules to signal out of control points in Shewhart charts.

`qccRules(object, rules = object$rules)`

## Arguments

- object
an object of class `'qcc'`

.

- rules
a vector of values specifying the rules used to declare a process out-of-control.
Possible values are:

- 1.
One point plots outside 3-sigma control limits.

- 2.
Two of three consecutive points plot beyond a 2-sigma limit.

- 3.
Four of five consecutive points plot beyond a 1-sigma limit.

- 4.
Eight consecutive points plot on one side of the center line.

These are often known as *Western Electric rules*.

## Value

The function returns a vector of the same length as the statistics charted with value `NA`

if no rule is violated, and numerical values corresponding to the violated rule. If more than one rule is violated, the value returned corresponds to the most serious violation.