StatControlCharts.QCCumSumChart Method

CUMSum chart.

public QCCumSumChart(TMtx Data, TVec DrawVec, double k, double h, double mean, double sigma, TVec SHigh, TVec SLow, double Confidence);

Parameters

Parameters	Description
Data	Each Data row contains replicated observation taken at specific time.
DrawVec	Returns values to be drawn.
k	Design parameter of the V-mask. k is the rise in the V-arm corresponding to one sampling unit.
h	Design parameter of the V-mask. h defines the rise in the arm coresponding to the distance from the origin to point vertex.
mean	Defines the estimate of the in-control mean.
sigma	Defines known (or estimated) standard deviation of the sample means.
SHigh	If set, returns high values for cumsum plot. When SHigh exceeds value h, the process is said to be out-of-control. Compare SHigh values to h to find if a process is out-of-control.
SLow	If set, returns low values for cumsum plot. When SLow exceeds value h, the process is said to be out-of-control. Compare SLow values to h to find if a process is out-of-control.
Confidence	Confidence level for upper and lower control limit. Confidence must lie in the (0,1) interval.

Remarks

Calculates CumSum Chart drawing values and additonal values, needed for deciding if some samples are out-of-control. See www.itl.nist.gov/div898/handbook/pmc/section3/pmc323.htm to learn more about Cumsum QC charts.

C# Example

Perform CumSum QC to determine if process is out-of-control.

using Dew.Math;
using Dew.Math.Units;
using Dew.Stats.Units;
namespace Dew.Examples
{
  private void Example()
  {
    Matrix data = new Matrix(0,0);
    data.LoadFromFile("process_data.mtx");

    Vector sh = new Vector(0);
    Vector sl = new Vector(0);
    Vector s = new Vector(0);
    Vector outofcontrol = new Vector(0);
    // estimate k=0.32, h = 4.7
    double k = 0.32;
    double h = 4.7;
    // estimate process mean and sigma
    double m = 230.3;
    double s = 5.2;
    StatControlCharts.QCCumSumChart(data,s,k,h,m,s,sh,sl);
    // find point indexes which exceed h (out-of-control points)
    outofcontrol.FindIndexes(shigh,">",h);
  }
}