Example usage for org.apache.commons.math.stat.inference ChiSquareTestImpl chiSquareTest

Introduction

In this page you can find the example usage for org.apache.commons.math.stat.inference ChiSquareTestImpl chiSquareTest.

Prototype

public boolean chiSquareTest(long[][] counts, double alpha) throws IllegalArgumentException, MathException 

Source Link

Usage

From source file:mlflex.EvaluationMetrics.java

private double CalculateLogRankStatisticMultipleGroups(SurvivalGroups survivalsList) throws Exception {
    double[] allExpected = new double[survivalsList.Size()];
    long[] allObserved = new long[survivalsList.Size()];

    HashMap<Integer, ArrayList<Double>> allTimesExpected = new HashMap<Integer, ArrayList<Double>>();

    for (int i = 0; i < survivalsList.Size(); i++)
        allTimesExpected.put(i, new ArrayList<Double>());

    for (double time : new ArrayList<Double>(
            Lists.Sort(new ArrayList(new HashSet<Double>(survivalsList.GetObservedTimes()))))) {
        double numAtRisk = Lists.GreaterThan(survivalsList.GetAllTimes(), time, true).size();
        double numDied = Lists.GetNumEqualTo(survivalsList.GetObservedTimes(), time);
        double riskOfDeath = numDied / numAtRisk;

        for (int i = 0; i < survivalsList.Size(); i++) {
            Survivals survivals = survivalsList.GetGroup(i);

            double numAllEvents = Lists.GreaterThan(survivals.GetAllTimes(), time, true).size();
            double numExpectedEvents = numAllEvents * riskOfDeath;

            allTimesExpected.get(i).add(numExpectedEvents);
        }/*from w w w  . j av a  2 s .c o  m*/
    }

    for (int i = 0; i < survivalsList.Size(); i++) {
        double expected = MathUtility.Sum(allTimesExpected.get(i));
        long observed = survivalsList.GetGroup(i).GetObservedTimes().size();

        allExpected[i] = expected;
        allObserved[i] = observed;
    }

    //http://commons.apache.org/math/api-2.1/index.html
    org.apache.commons.math.stat.inference.ChiSquareTestImpl chi = new org.apache.commons.math.stat.inference.ChiSquareTestImpl();
    double chiSquareP = chi.chiSquareTest(allExpected, allObserved);

    return chiSquareP;
}

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