de.jstacs.classifiers.utils
Class PValueComputation

java.lang.Object
  de.jstacs.classifiers.utils.PValueComputation

public class PValueComputation
extends Object

This class can be used to compute any p-value from a given statistic. Therefore the array of scores has to be sorted.

Author:

Jens Keilwagen

See Also:

Arrays.sort(double[])

Constructor Summary

PValueComputation()

Method Summary

static int	getBorder(double[] sortedScores, double pValue) This method finds the first index that has a significant score.
static int	getIndex(double[] sortedScores, double myScore) This method searches in sortedScores for the index i so that sortedScores[i-1] < myScore <= sortedScores[i].
static int	getIndex(double[] sortedScores, double myScore, int start) This method searches in sortedScores beginning at start for the index i so that sortedScores[i-1] < myScore <= sortedScores[i].
static double	getPValue(double[] sortedScores, double myScore) This method searches for the insertion point of the score in a given sorted array of scores and returns the p-value for this score.
static double	getPValue(double[] sortedScores, double myScore, int start) This method searches for the insertion point of the score in a given sorted array of scores from index start and returns the p-value for this score.
static double	getThreshold(double[] sortedScores, int signIndex) This method returns the threshold that determines if an observed score is significant.

Methods inherited from class java.lang.Object

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

Constructor Detail

PValueComputation

public PValueComputation()

Method Detail

getPValue

public static final double getPValue(double[] sortedScores,
                                     double myScore)

This method searches for the insertion point of the score in a given sorted array of scores and returns the p-value for this score.

Parameters:

sortedScores - the array of sorted scores

myScore - the score that is searched in the array and that corresponds to the p-value

Returns:

the p-value for the score

See Also:

Arrays.sort(double[]), getIndex(double[], double)

getPValue

public static final double getPValue(double[] sortedScores,
                                     double myScore,
                                     int start)

This method searches for the insertion point of the score in a given sorted array of scores from index start and returns the p-value for this score.

Parameters:

sortedScores - the array of sorted scores

myScore - the score that is searched in the array and that corresponds to the p-value

start - the start position in the array where to start the search (accelerates the search)

Returns:

the p-value for the score

See Also:

Arrays.sort(double[]), getIndex(double[], double, int)

getIndex

public static final int getIndex(double[] sortedScores,
                                 double myScore)

This method searches in sortedScores for the index i so that sortedScores[i-1] < myScore <= sortedScores[i]. This index could be seen as insertion point for myScore.

Parameters:

sortedScores - the array of sorted scores

myScore - the current score

Returns:

the index where myScore should be inserted

See Also:

Arrays.sort(double[]), getIndex(double[], double, int)

getIndex

public static final int getIndex(double[] sortedScores,
                                 double myScore,
                                 int start)

This method searches in sortedScores beginning at start for the index i so that sortedScores[i-1] < myScore <= sortedScores[i]. This index could be seen as insertion point for myScore.

Parameters:

sortedScores - the array of sorted scores

myScore - the current score

start - the start index (inclusive)

Returns:

the index where myScore should be inserted

See Also:

Arrays.sort(double[])

getBorder

public static final int getBorder(double[] sortedScores,
                                  double pValue)

This method finds the first index that has a significant score.

Parameters:

sortedScores - the array of sorted scores

pValue - the p-value that is used to determine what is significant and what not (the smaller, the more significant)

Returns:

the index of the first significant score

See Also:

Arrays.sort(double[])

getThreshold

public static final double getThreshold(double[] sortedScores,
                                        int signIndex)

This method returns the threshold that determines if an observed score is significant. The observed score is significant if it is bigger than the threshold.

Parameters:

sortedScores - the array of sorted scores

signIndex - the index of the first significant score

Returns:

the threshold