PChart is a p-chart for monitoring the defect rate when defects are not rare.

Namespace: Imsl.Chart2D.QC
Assembly: ImslCS (in ImslCS.dll) Version: 6.5.0.0

Syntax

C#
[SerializableAttribute]
public class PChart : ShewhartControlChart
Visual Basic (Declaration)
<SerializableAttribute> _
Public Class PChart _
	Inherits ShewhartControlChart
Visual C++
[SerializableAttribute]
public ref class PChart : public ShewhartControlChart

Remarks

The defect rate is the number of defects found divided by the number of samples inspected. The number of defects are not assumed to be rare. Control limits are computed using the binomial distribution. If defects are rare, use UChart instead.

The control limits are at

\bar{p}+k\sqrt{\frac{\bar{p}(1-\bar{p})}{n}}
where \bar{p} is the mean defect rate, n is the sample size, and k is the value of the "ControlLimit" attribute for the line. By default, the chart contains an upper control limit line with k=3, a lower control limit line with k=-3, and a central line equal to \bar{p}. Additional control limits can be added. The method AddWeco adds control limits with k = -2, -1, 1, 2.

The true fraction conforming p can be used by setting the attribute "Center" to p.

The lower control limit is forced to have a minimum value of zero. The upper control limit is forced to have a maximum value of one.

Inheritance Hierarchy

See Also