UChart is a u-chart for monitoring the defect rate when defects are rare.

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

Syntax

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

Remarks

The defect rate is the number of defects found divided by the number of samples inspected. The number of defects are assumed to be rare. Control limits are computed using the Poisson distribution. If defects are not rare, use PChart instead. The sample sizes are not required to be equal.

The control limits are at

\bar{u}+k\sqrt{\bar{u}/n}
where \bar{u} is the observed average number of defects per unit, n is the number of inspection units, 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{u}. Additional control limits can be added. The method AddWeco adds control limits with k = -2, -1, 1, 2.

Inheritance Hierarchy

See Also