MOEA Framework 2.12
API Specification

org.moeaframework.util.statistics
Class TwoSampleTTest

java.lang.Object
  extended by org.moeaframework.util.statistics.IntervalRatioStatisticalTest
      extended by org.moeaframework.util.statistics.TwoSampleTTest
All Implemented Interfaces:
StatisticalTest

public class TwoSampleTTest
extends IntervalRatioStatisticalTest

The Two-Sample t test determines if the mean of two populations are different. The independent flag in the constructor is used to choose between the unpaired (independent) and paired (dependent) test.

Assumptions:

  1. Samples are randomly selected from the corresponding population
  2. The distribution of the underlying populations is normal

References:

  1. Sheskin, D.J. "Handbook of Parametric and Nonparametric Statistical Procedures, Third Edition." Chapman & Hall/CRC. 2004.


Field Summary
 
Fields inherited from class org.moeaframework.util.statistics.IntervalRatioStatisticalTest
data, numberOfGroups
 
Constructor Summary
TwoSampleTTest(boolean independent)
          Constructs a two sample T test.
 
Method Summary
 void add(double value, int group)
          Adds a new observation with the specified value and group.
 void addAll(double[] values, int group)
          Adds several new observations to the specified group.
 boolean test(double alpha)
          Returns true if the null hypothesis is rejected; false otherwise.
 
Methods inherited from class org.moeaframework.util.statistics.IntervalRatioStatisticalTest
categorize, getNumberOfGroups
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

TwoSampleTTest

public TwoSampleTTest(boolean independent)
Constructs a two sample T test.

Parameters:
independent - uses the unpaired T test if true; the paired T test if false
Method Detail

add

public void add(double value,
                int group)
Description copied from class: IntervalRatioStatisticalTest
Adds a new observation with the specified value and group.

Overrides:
add in class IntervalRatioStatisticalTest
Parameters:
value - the value of the new observation
group - the group to which the new observation belongs

addAll

public void addAll(double[] values,
                   int group)
Description copied from class: IntervalRatioStatisticalTest
Adds several new observations to the specified group.

Overrides:
addAll in class IntervalRatioStatisticalTest
Parameters:
values - the values of the new observations
group - the group to which the new observations belong

test

public boolean test(double alpha)
Returns true if the null hypothesis is rejected; false otherwise. The meaning of the null hypothesis and alternative hypothesis depends on the specific test.

The prespecified level of confidence, alpha, can be used for either one-tailed or two-tailed (directional or nondirectional) distributions, depending on the specific test. Some tests may only support specific values for alpha.

Parameters:
alpha - the prespecified level of confidence
Returns:
true if the null hypothesis is rejected; false otherwise
See Also:
TestUtils.tTest(double[], double[], double), TestUtils.pairedTTest(double[], double[], double)

MOEA Framework 2.12
API Specification

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