geogebra.common.kernel.statistics.AlgoZProportion2Test.java Source code

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Here is the source code for geogebra.common.kernel.statistics.AlgoZProportion2Test.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.common.kernel.statistics;

import geogebra.common.kernel.Construction;
import geogebra.common.kernel.algos.AlgoElement;
import geogebra.common.kernel.commands.Commands;
import geogebra.common.kernel.geos.GeoElement;
import geogebra.common.kernel.geos.GeoList;
import geogebra.common.kernel.geos.GeoNumeric;
import geogebra.common.kernel.geos.GeoText;
import geogebra.common.util.StringUtil;

import org.apache.commons.math.distribution.NormalDistributionImpl;

/**
 * 
 * 
 * @author G. Sturr
 */
public class AlgoZProportion2Test extends AlgoElement {

    private GeoNumeric proportion, n, proportion2, n_2; // input
    private GeoText tail; // input
    private GeoList result; // output
    private double se;

    /**
     * @param cons
     * @param label
     * @param proportion
     * @param n
     * @param proportion2
     * @param n_2
     * @param tail
     */
    public AlgoZProportion2Test(Construction cons, String label, GeoNumeric proportion, GeoNumeric n,
            GeoNumeric proportion2, GeoNumeric n_2, GeoText tail) {
        this(cons, proportion, n, proportion2, n_2, tail);
        result.setLabel(label);
    }

    /**
     * @param cons
     * @param proportion
     * @param n
     * @param proportion2
     * @param n_2
     * @param tail
     */
    public AlgoZProportion2Test(Construction cons, GeoNumeric proportion, GeoNumeric n, GeoNumeric proportion2,
            GeoNumeric n_2, GeoText tail) {
        super(cons);
        this.tail = tail;
        this.proportion = proportion;
        this.n = n;
        this.proportion2 = proportion2;
        this.n_2 = n_2;
        result = new GeoList(cons);
        setInputOutput(); // for AlgoElement

        compute();
    }

    @Override
    public Commands getClassName() {
        return Commands.ZProportionTest;
    }

    @Override
    protected void setInputOutput() {

        input = new GeoElement[5];
        input[0] = proportion;
        input[1] = n;
        input[2] = proportion2;
        input[3] = n_2;
        input[4] = tail;

        setOnlyOutput(result);
        setDependencies(); // done by AlgoElement
    }

    /**
     * @return {P value, Z test statistic}
     */
    public GeoList getResult() {
        return result;
    }

    /**
     * @return standard error
     */
    public double getSE() {
        return se;
    }

    @Override
    public final void compute() {

        String testType;
        if (tail.getTextString().equals("<")) {
            testType = "left";
        } else if (tail.getTextString().equals(">")) {
            testType = "right";
        } else if (StringUtil.isNotEqual(tail.getTextString())) {
            testType = "two";
        } else {
            result.setUndefined();
            return;
        }

        double n1 = n.getDouble();
        double phat1 = proportion.getDouble();
        double n2 = n_2.getDouble();
        double phat2 = proportion2.getDouble();

        double x1 = phat1 * n1;
        double x2 = phat2 * n2;
        double phatTotal = (x1 + x2) / (n1 + n2);
        se = Math.sqrt(phatTotal * (1 - phatTotal) * (1 / n1 + 1 / n2));
        double testStatistic = (phat1 - phat2) / se;

        NormalDistributionImpl normalDist = new NormalDistributionImpl(0, 1);
        double P = 0;
        try {
            P = normalDist.cumulativeProbability(testStatistic);
        } catch (Exception e) {
            result.setUndefined();
            return;
        }

        if ("right".equals(testType)) {
            P = 1 - P;
        } else if ("two".equals(testType)) {
            if (testStatistic < 0) {
                P = 2 * P;
            } else {
                P = 2 * (1 - P);
            }
        }

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

    }

}