JMSL Chart Guide: XmR

JMSL Chart Programmer's Guide

Quality Control and Improvement Charts >> XmR

XmR

XmR is a moving range chart. It is used when only samples of size one are available. The moving range statistic is

The control limits are computed using

Where is the mean of the observations, is the mean of the moving ranges and

is the mean of the distribution of the ranges of n samples from the normal distribution with mean of zero and standard deviation of one.

XmR Example

The viscosity of aircraft primer paint was measured. Since the paint is produced in batches, only single samples are available (Montgomery 251).

(Download Code)

import com.imsl.chart.*;
import com.imsl.chart.qc.*;

public class SampleXmR extends JFrameChart {
    static final double viscosity[] = {
        33.75, 33.05, 34.00, 33.81, 33.46, 34.02, 33.68,
        33.27, 33.49, 33.20, 33.62, 33.00, 33.54, 33.12, 33.84
    };   
    
    public SampleXmR() {
        Chart chart = getChart();
        AxisXY axis = new AxisXY(chart);
        XmR xmr = new XmR(axis, viscosity);
    }
    
    public static void main(String argv[]) {
        new SampleXmR().setVisible(true);
    }
}