How to use

getVariance

method

in

org.apache.commons.math.stat.descriptive.StatisticalSummary

@Override
protected Serializable reduceValues(final List<Object> slaveValues, final String column, final String measure,
    final Collection<? extends NumberAnalyzerResult> results, final Class<?> valueClass) {
  if (SUM_MEASURES.contains(measure)) {
    return sum(slaveValues);
  } else if (NumberAnalyzer.MEASURE_HIGHEST_VALUE.equals(measure)) {
    return maximum(slaveValues);
  } else if (NumberAnalyzer.MEASURE_LOWEST_VALUE.equals(measure)) {
    return minimum(slaveValues);
  } else if (NumberAnalyzer.MEASURE_MEAN.equals(measure)) {
    final StatisticalSummary summary = getSummary(column, results);
    return summary.getMean();
  } else if (NumberAnalyzer.MEASURE_STANDARD_DEVIATION.equals(measure)) {
    final StatisticalSummary summary = getSummary(column, results);
    return summary.getStandardDeviation();
  } else if (NumberAnalyzer.MEASURE_VARIANCE.equals(measure)) {
    final StatisticalSummary summary = getSummary(column, results);
    return summary.getVariance();
  }
  logger.warn("Encountered non-reduceable measure '{}'. Slave values are: {}", measure, slaveValues);
  return null;
}

@Override
protected Serializable reduceValues(List<Object> slaveValues, String column, String measure,
    Collection<? extends NumberAnalyzerResult> results, Class<?> valueClass) {
  if (SUM_MEASURES.contains(measure)) {
    return sum(slaveValues);
  } else if (NumberAnalyzer.MEASURE_HIGHEST_VALUE.equals(measure)) {
    return maximum(slaveValues);
  } else if (NumberAnalyzer.MEASURE_LOWEST_VALUE.equals(measure)) {
    return minimum(slaveValues);
  } else if (NumberAnalyzer.MEASURE_MEAN.equals(measure)) {
    StatisticalSummary summary = getSummary(column, results);
    return summary.getMean();
  } else if (NumberAnalyzer.MEASURE_STANDARD_DEVIATION.equals(measure)) {
    StatisticalSummary summary = getSummary(column, results);
    return summary.getStandardDeviation();
  } else if (NumberAnalyzer.MEASURE_VARIANCE.equals(measure)) {
    StatisticalSummary summary = getSummary(column, results);
    return summary.getVariance();
  }
  
  logger.warn("Encountered non-reduceable measure '{}'. Slave values are: {}", measure, slaveValues);
  return null;
}

/**
 * Computes a <a href="http://www.itl.nist.gov/div898/handbook/prc/section2/prc22.htm#formula">
 * t statistic </a> to use in comparing the mean of the dataset described by 
 * <code>sampleStats</code> to <code>mu</code>.
 * <p>
 * This statistic can be used to perform a one sample t-test for the mean.
 * </p><p>
 * <strong>Preconditions</strong>: <ul>
 * <li><code>observed.getN() > = 2</code>.
 * </li></ul></p>
 *
 * @param mu comparison constant
 * @param sampleStats DescriptiveStatistics holding sample summary statitstics
 * @return t statistic
 * @throws IllegalArgumentException if the precondition is not met
 */
public double t(double mu, StatisticalSummary sampleStats)
throws IllegalArgumentException {
  if ((sampleStats == null) || (sampleStats.getN() < 2)) {
    throw new IllegalArgumentException("insufficient data for t statistic");
  }
  return t(sampleStats.getMean(), mu, sampleStats.getVariance(),
      sampleStats.getN());
}

  throw new IllegalArgumentException("insufficient data for t statistic");
return tTest(sampleStats1.getMean(), sampleStats2.getMean(), sampleStats1.getVariance(),
    sampleStats2.getVariance(), (double) sampleStats1.getN(), 
    (double) sampleStats2.getN());

sampleStats2.getMean(), sampleStats1.getVariance(),
sampleStats2.getVariance(), (double) sampleStats1.getN(), 
(double) sampleStats2.getN());

sampleStats1.getVariance(), sampleStats2.getVariance(),
(double) sampleStats1.getN(), (double) sampleStats2.getN());

  throw new IllegalArgumentException("insufficient data for t statistic");
return tTest(sampleStats.getMean(), mu, sampleStats.getVariance(),
    sampleStats.getN());

sampleStats1.getVariance(), sampleStats2.getVariance(), 
(double) sampleStats1.getN(), (double) sampleStats2.getN());

checkSampleData(sampleStats1);
checkSampleData(sampleStats2);
return tTest(sampleStats1.getMean(), sampleStats2.getMean(), sampleStats1.getVariance(),
    sampleStats2.getVariance(), sampleStats1.getN(),
    sampleStats2.getN());

/**
 * Computes a <a href="http://www.itl.nist.gov/div898/handbook/prc/section2/prc22.htm#formula">
 * t statistic </a> to use in comparing the mean of the dataset described by
 * <code>sampleStats</code> to <code>mu</code>.
 * <p>
 * This statistic can be used to perform a one sample t-test for the mean.
 * </p><p>
 * <strong>Preconditions</strong>: <ul>
 * <li><code>observed.getN() > = 2</code>.
 * </li></ul></p>
 *
 * @param mu comparison constant
 * @param sampleStats DescriptiveStatistics holding sample summary statitstics
 * @return t statistic
 * @throws IllegalArgumentException if the precondition is not met
 */
public double t(double mu, StatisticalSummary sampleStats)
throws IllegalArgumentException {
  checkSampleData(sampleStats);
  return t(sampleStats.getMean(), mu, sampleStats.getVariance(),
      sampleStats.getN());
}

/**
 * Computes a <a href="http://www.itl.nist.gov/div898/handbook/prc/section2/prc22.htm#formula">
 * t statistic </a> to use in comparing the mean of the dataset described by
 * <code>sampleStats</code> to <code>mu</code>.
 * <p>
 * This statistic can be used to perform a one sample t-test for the mean.
 * </p><p>
 * <strong>Preconditions</strong>: <ul>
 * <li><code>observed.getN() > = 2</code>.
 * </li></ul></p>
 *
 * @param mu comparison constant
 * @param sampleStats DescriptiveStatistics holding sample summary statitstics
 * @return t statistic
 * @throws IllegalArgumentException if the precondition is not met
 */
public double t(double mu, StatisticalSummary sampleStats)
throws IllegalArgumentException {
  checkSampleData(sampleStats);
  return t(sampleStats.getMean(), mu, sampleStats.getVariance(),
      sampleStats.getN());
}

checkSampleData(sampleStats2);
return homoscedasticTTest(sampleStats1.getMean(),
    sampleStats2.getMean(), sampleStats1.getVariance(),
    sampleStats2.getVariance(), sampleStats1.getN(),
    sampleStats2.getN());

checkSampleData(sampleStats2);
return homoscedasticT(sampleStats1.getMean(), sampleStats2.getMean(),
    sampleStats1.getVariance(), sampleStats2.getVariance(),
    sampleStats1.getN(), sampleStats2.getN());

checkSampleData(sampleStats2);
return t(sampleStats1.getMean(), sampleStats2.getMean(),
    sampleStats1.getVariance(), sampleStats2.getVariance(),
    sampleStats1.getN(), sampleStats2.getN());

checkSampleData(sampleStats2);
return homoscedasticTTest(sampleStats1.getMean(),
    sampleStats2.getMean(), sampleStats1.getVariance(),
    sampleStats2.getVariance(), sampleStats1.getN(),
    sampleStats2.getN());

checkSampleData(sampleStats2);
return homoscedasticT(sampleStats1.getMean(), sampleStats2.getMean(),
    sampleStats1.getVariance(), sampleStats2.getVariance(),
    sampleStats1.getN(), sampleStats2.getN());

checkSampleData(sampleStats2);
return t(sampleStats1.getMean(), sampleStats2.getMean(),
    sampleStats1.getVariance(), sampleStats2.getVariance(),
    sampleStats1.getN(), sampleStats2.getN());

checkSampleData(sampleStats1);
checkSampleData(sampleStats2);
return tTest(sampleStats1.getMean(), sampleStats2.getMean(), sampleStats1.getVariance(),
    sampleStats2.getVariance(), sampleStats1.getN(),
    sampleStats2.getN());

throws IllegalArgumentException, MathException {
  checkSampleData(sampleStats);
  return tTest(sampleStats.getMean(), mu, sampleStats.getVariance(),
      sampleStats.getN());

throws IllegalArgumentException, MathException {
  checkSampleData(sampleStats);
  return tTest(sampleStats.getMean(), mu, sampleStats.getVariance(),
      sampleStats.getN());