dev.nm.stat.descriptive.rank

Class Rank

java.lang.Object

dev.nm.stat.descriptive.rank.Rank

public class Rank
extends Object

Rank is a relationship between a set of items such that, for any two items, the first is either "ranked higher than", "ranked lower than" or "ranked equal to" the second. This is known as a weak order or total preorder of objects. It is not necessarily a total order of objects because two different objects can have the same ranking. The rankings themselves are totally ordered. In statistics, "ranking" refers to the data transformation in which numerical or ordinal values are replaced by their rank when the data are sorted. It is important to note that ranks can sometimes have non-integer values for tied data values. Thus, in one way of treating tied data values, when there is an even number of copies of the same data value, the statistical rank (being the median rank of the tied data) can end in ½ or another fraction. The R equivalent function is rank.

See Also:

• Wikipedia: Ranking
• Wikipedia: Ranking in statistics

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Rank.TiesMethod The method for assigning ranks when some values are equal (called 'ties').

Constructor Summary

Constructors

Constructor and Description
Rank(double[] values) Compute the sample ranks of the values.
Rank(double[] values, double threshold) Compute the sample ranks of the values.
Rank(double[] values, double threshold, Rank.TiesMethod tiesMethod) Compute the sample ranks of the values.
Rank(double[] values, Rank.TiesMethod tiesMethod) Compute the sample ranks of the values.

Method Summary

Modifier and Type	Method and Description
double	rank(int i) Get the rank of the i-th element.
double[]	ranks() Get the ranks of the values.
double	s() \[ s = \sum(t_i^2 - t_i) \]
double	t() \[ t = \sum(t_i^3 - t_i) \]

Methods inherited from class java.lang.Object

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

Constructor Detail

Rank

public Rank(double[] values)

Compute the sample ranks of the values. Use Rank.TiesMethod.AS_26 as the default method for breaking ties.

Parameters:

values - the values

Rank

public Rank(double[] values,
            double threshold)

Compute the sample ranks of the values. Use Rank.TiesMethod.AS_26 as the default method for breaking ties.

Parameters:

values - the values

threshold - the tie threshold. If successive elements of the sorted array differ by less than the threshold, they are treated as equal. We count the number of ties in each group.

Rank

public Rank(double[] values,
            Rank.TiesMethod tiesMethod)

Compute the sample ranks of the values.

Parameters:

values - the values

tiesMethod - the method that determines ranks for ties

Rank

public Rank(double[] values,
            double threshold,
            Rank.TiesMethod tiesMethod)

Compute the sample ranks of the values.

Parameters:

values - the values

threshold - the tie threshold. If successive elements of the sorted array differ by less than the threshold, they are treated as equal. We count the number of ties in each group.

tiesMethod - the method that determines ranks for ties

Method Detail

rank

public double rank(int i)

Get the rank of the i-th element.

Parameters:

i - the index to a value

Returns:

the rank of the i-th element

ranks

public double[] ranks()

Get the ranks of the values.

Returns:

the ranks

t

public double t()

\[ t = \sum(t_i^3 - t_i) \]

Returns:

t

s

public double s()

\[ s = \sum(t_i^2 - t_i) \]

Returns:

s