Example usage for org.apache.commons.math.distribution ChiSquaredDistributionImpl cumulativeProbability

Introduction

In this page you can find the example usage for org.apache.commons.math.distribution ChiSquaredDistributionImpl cumulativeProbability.

Prototype

public double cumulativeProbability(double x) throws MathException 

Source Link

Document

For this distribution, X, this method returns P(X < x).

Usage

From source file:mlflex.EvaluationMetrics.java

private double CalculateLogRankStatisticTwoGroups(SurvivalGroups survivalsList) throws Exception {
    ArrayList<Double> allDiff1 = new ArrayList<Double>();
    ArrayList<Double> allVar = new ArrayList<Double>();

    for (double time : new ArrayList<Double>(
            Lists.Sort(new ArrayList(new HashSet<Double>(survivalsList.GetObservedTimes()))))) {
        double n = Lists.GreaterThan(survivalsList.GetAllTimes(), time, true).size();
        double n1 = Lists.GreaterThan(survivalsList.GetGroup(0).GetAllTimes(), time, true).size();
        double n2 = Lists.GreaterThan(survivalsList.GetGroup(1).GetAllTimes(), time, true).size();
        double e = Lists.GetNumEqualTo(survivalsList.GetObservedTimes(), time);
        double e1 = Lists.GetNumEqualTo(survivalsList.GetGroup(0).GetObservedTimes(), time);
        double exp1 = e * (n1 / n);
        double var = n <= 1.0 ? 0.0 : (n1 * n2 * e * (n - e)) / (n * n * (n - 1));

        allDiff1.add(e1 - exp1);/*from   w w  w . j  a v  a2s.  co  m*/
        allVar.add(var);
    }

    double logRankStatistic = Math.pow(MathUtility.Sum(allDiff1), 2.0) / MathUtility.Sum(allVar);

    org.apache.commons.math.distribution.ChiSquaredDistributionImpl chi = new ChiSquaredDistributionImpl(
            survivalsList.Size() - 1);
    double chiSquareP = 1 - chi.cumulativeProbability(logRankStatistic);

    return chiSquareP;
}

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