org.android.activityminer.logic.statistics
Class StudentTTest

java.lang.Object
  org.android.activityminer.logic.statistics.StudentTTest

public class StudentTTest
extends Object

Am simple Student t test implementation to generate a X%, two-sided mean confidence interval for one sample.

Nested Class Summary

static class

StudentTTest.ConfidenceCoefficent Known confidence coefficients (for confidence interval calculation)

Field Summary

private static double[][]

table Critical values of Student's t distribution with ν (v<10) degrees of freedom.

Constructor Summary

StudentTTest()

Method Summary

static double	meanConfidenceDelta(double[] sample, StudentTTest.ConfidenceCoefficent cc) Mean confidence delta computation for a single sample.
private static double	meanConfidenceDelta(double mean, double var, int n, StudentTTest.ConfidenceCoefficent cc) Mean confidence delta computation.
static double[]	meanConfidenceInterval(double[] sample, StudentTTest.ConfidenceCoefficent cc) Mean confidence interval computation for a single sample.
private static double[]	meanConfidenceInterval(double mean, double var, int n, StudentTTest.ConfidenceCoefficent cc) Mean confidence interval computation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

table

private static final double[][] table

Critical values of Student's t distribution with ν (v<10) degrees of freedom. Values have benn calculated with R: qt(1-α/2,df=v).

Constructor Detail

StudentTTest

public StudentTTest()

Method Detail

meanConfidenceDelta

private static final double meanConfidenceDelta(double mean,
                                                double var,
                                                int n,
                                                StudentTTest.ConfidenceCoefficent cc)
                                         throws IllegalArgumentException

Mean confidence delta computation.

Parameters:

mean - the sample mean

var - the sample variance

n - the sample count

cc - the confidence coefficient (1-significance)

Returns:

the confidence delta from the mean (mean +- result is the interval)

Throws:

IllegalArgumentException - if n is not more than 1

meanConfidenceDelta

public static final double meanConfidenceDelta(double[] sample,
                                               StudentTTest.ConfidenceCoefficent cc)
                                        throws IllegalArgumentException

Mean confidence delta computation for a single sample.

Parameters:

sample - the sample

cc - the confidence coefficient (1-significance)

Returns:

the confidence delta from the mean (mean +- result is the interval)

Throws:

IllegalArgumentException - if n is not more than 1

meanConfidenceInterval

private static final double[] meanConfidenceInterval(double mean,
                                                     double var,
                                                     int n,
                                                     StudentTTest.ConfidenceCoefficent cc)
                                              throws IllegalArgumentException

Mean confidence interval computation.

Parameters:

mean - the sample mean

var - the sample variance

n - the sample count

cc - the confidence coefficient (1-significance)

Returns:

the confidence intervals lower and upper bound

Throws:

IllegalArgumentException - if n is not more than 1

meanConfidenceInterval

public static final double[] meanConfidenceInterval(double[] sample,
                                                    StudentTTest.ConfidenceCoefficent cc)
                                             throws IllegalArgumentException

Mean confidence interval computation for a single sample.

Parameters:

sample - the sample

cc - the confidence coefficient (1-significance)

Returns:

the confidence intervals lower and upper bound

Throws:

IllegalArgumentException - if n is not more than 1