RChart is an R chart using sample ranges to monitor the variability of a process. Each sample must contain at least two observations. The range of a sample is the maximum observed value minus the minimum observed value.

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

Syntax

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

Remarks

The control limits are at

\bar{R} + k \frac{d_{3,n}}{d_{2,n}}\bar{R}
\bar{R} is the mean of the observed ranges, n is the sample size, and k is the value of the "ControlLimit" attribute for the line. Additionally, d_{2,n} is the mean of the distribution of the ranges of n samples from the normal distribution with mean zero and standard deviation one. The standard deviation of this distribution is d_{3,n}. Therefore
\frac{d_{3,n}}{d_{2,n}}\bar{R}
is an estimator of the standard deviation of the ranges.

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 with k=0. Additional control limit lines can be added. The method AddWeco adds control limit lines with k = -2, -1, 1, 2.

Inheritance Hierarchy

See Also