geogebra.kernel.statistics.AlgoTTest.java Source code

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Here is the source code for geogebra.kernel.statistics.AlgoTTest.java

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/* 
GeoGebra - Dynamic Mathematics for Everyone
http://www.geogebra.org
    
This file is part of GeoGebra.
    
This program is free software; you can redistribute it and/or modify it 
under the terms of the GNU General Public License as published by 
the Free Software Foundation.
    
 */

package geogebra.kernel.statistics;

import geogebra.kernel.AlgoElement;
import geogebra.kernel.Construction;
import geogebra.kernel.GeoElement;
import geogebra.kernel.GeoList;
import geogebra.kernel.GeoNumeric;
import geogebra.kernel.GeoText;
import geogebra.kernel.arithmetic.NumberValue;

import org.apache.commons.math.MathException;
import org.apache.commons.math.stat.descriptive.StatisticalSummaryValues;
import org.apache.commons.math.stat.inference.TTestImpl;

/**
 * Performs a one sample t-test of a mean.
 * 
 * 
 * @author G. Sturr
 */
public class AlgoTTest extends AlgoElement {

    private static final long serialVersionUID = 1L;
    private GeoList geoList; //input
    private GeoNumeric hypMean, mean, sd, n; //input
    private GeoText tail; //input
    private GeoList result; // output   
    private TTestImpl tTestImpl;
    private double[] val;
    private double p, testStat;

    public AlgoTTest(Construction cons, String label, GeoList geoList, GeoNumeric hypMean, GeoText tail) {
        super(cons);
        this.geoList = geoList;
        this.hypMean = hypMean;
        this.tail = tail;
        this.mean = null;
        this.sd = null;
        this.n = null;
        result = new GeoList(cons);
        setInputOutput(); // for AlgoElement

        compute();
        result.setLabel(label);
    }

    public AlgoTTest(Construction cons, String label, GeoNumeric mean, GeoNumeric sd, GeoNumeric n,
            GeoNumeric hypMean, GeoText tail) {
        super(cons);
        this.geoList = null;
        this.hypMean = hypMean;
        this.tail = tail;
        this.mean = mean;
        this.sd = sd;
        this.n = n;
        result = new GeoList(cons);
        setInputOutput(); // for AlgoElement

        compute();
        result.setLabel(label);
    }

    public String getClassName() {
        return "AlgoTTest";
    }

    protected void setInputOutput() {

        if (geoList != null) {
            input = new GeoElement[3];
            input[0] = geoList;
            input[1] = hypMean;
            input[2] = tail;

        } else {
            input = new GeoElement[5];
            input[0] = mean;
            input[1] = sd;
            input[2] = n;
            input[3] = hypMean;
            input[4] = tail;
        }

        output = new GeoElement[1];
        output[0] = result;
        setDependencies(); // done by AlgoElement
    }

    public GeoList getResult() {
        return result;
    }

    private double adjustedPValue(double p, double testStatistic) {

        // two sided test
        if (tail.getTextString().equals("!=") || tail.getTextString().equals(""))
            return p;

        // one sided test
        else if ((tail.getTextString().equals(">") && testStatistic > 0)
                || (tail.getTextString().equals("<") && testStatistic < 0))
            return p / 2;
        else
            return 1 - p / 2;
    }

    protected final void compute() {

        if (!(tail.getTextString().equals("<") || tail.getTextString().equals(">")
                || tail.getTextString().equals("!=") || tail.getTextString().equals(""))) {
            result.setUndefined();
            return;
        }

        // sample data input
        if (input.length == 3) {

            int size = geoList.size();
            if (!geoList.isDefined() || size < 2) {
                result.setUndefined();
                return;
            }

            val = new double[size];

            for (int i = 0; i < size; i++) {
                GeoElement geo = geoList.get(i);
                if (geo.isNumberValue()) {
                    NumberValue num = (NumberValue) geo;
                    val[i] = num.getDouble();

                } else {
                    result.setUndefined();
                    return;
                }
            }

            try {

                // get the test statistic and p
                if (tTestImpl == null)
                    tTestImpl = new TTestImpl();
                testStat = tTestImpl.t(hypMean.getDouble(), val);
                p = tTestImpl.tTest(hypMean.getDouble(), val);
                p = adjustedPValue(p, testStat);

                // put these results into the output list
                result.clear();
                result.add(new GeoNumeric(cons, p));
                result.add(new GeoNumeric(cons, testStat));

            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (MathException e) {
                e.printStackTrace();
            }

            // sample statistics input 
        } else {

            // check for valid standard deviation and sample size
            if (sd.getDouble() < 0 || n.getDouble() < 2) {
                result.setUndefined();
                return;
            }
            StatisticalSummaryValues sumStats = new StatisticalSummaryValues(mean.getDouble(),
                    sd.getDouble() * sd.getDouble(), (long) n.getDouble(), -1, -1, -1);

            try {

                // get the test statistic and p
                if (tTestImpl == null)
                    tTestImpl = new TTestImpl();
                testStat = tTestImpl.t(hypMean.getDouble(), sumStats);
                p = tTestImpl.tTest(hypMean.getDouble(), sumStats);
                p = adjustedPValue(p, testStat);

                // put these results into the output list
                result.clear();
                result.add(new GeoNumeric(cons, p));
                result.add(new GeoNumeric(cons, testStat));

            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (MathException e) {
                e.printStackTrace();
            }

        }

    }

}