com.yahoo.sketches

Class BoundsOnRatiosInSampledSets

java.lang.Object

com.yahoo.sketches.BoundsOnRatiosInSampledSets

public final class BoundsOnRatiosInSampledSets
extends Object

This class is used to compute the bounds on the estimate of the ratio |B| / |A|, where:

• |A| is the unknown size of a set A of unique identifiers.
• |B| is the unknown size of a subset B of A.
• a = |S_A| is the observed size of a sample of A that was obtained by Bernoulli sampling with a known inclusion probability f.
• b = |S_A ∩ B| is the observed size of a subset of S_A.

Author:

Kevin Lang

Method Summary

Modifier and Type	Method and Description
static double	getEstimateOfA(long a, double f) Return the estimate of A.
static double	getEstimateOfB(long b, double f) Return the estimate of B.
static double	getEstimateOfBoverA(long a, long b) Return the estimate of b over a
static double	getLowerBoundForBoverA(long a, long b, double f) Return the approximate lower bound based on a 95% confidence interval
static double	getUpperBoundForBoverA(long a, long b, double f) Return the approximate upper bound based on a 95% confidence interval

Methods inherited from class java.lang.Object

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

Method Detail

getLowerBoundForBoverA

public static double getLowerBoundForBoverA(long a,
                                            long b,
                                            double f)

Return the approximate lower bound based on a 95% confidence interval

Parameters:

a - See class javadoc

b - See class javadoc

f - the inclusion probability used to produce the set with size a and should generally be less than 0.5. Above this value, the results not be reliable. When f = 1.0 this returns the estimate.

Returns:

the approximate upper bound

getUpperBoundForBoverA

public static double getUpperBoundForBoverA(long a,
                                            long b,
                                            double f)

Return the approximate upper bound based on a 95% confidence interval

Parameters:

a - See class javadoc

b - See class javadoc

f - the inclusion probability used to produce the set with size a.

Returns:

the approximate lower bound

getEstimateOfBoverA

public static double getEstimateOfBoverA(long a,
                                         long b)

Return the estimate of b over a

Parameters:

a - See class javadoc

b - See class javadoc

Returns:

the estimate of b over a

getEstimateOfA

public static double getEstimateOfA(long a,
                                    double f)

Return the estimate of A. See class javadoc.

Parameters:

a - See class javadoc

f - the inclusion probability used to produce the set with size a.

Returns:

the approximate lower bound

getEstimateOfB

public static double getEstimateOfB(long b,
                                    double f)

Return the estimate of B. See class javadoc.

Parameters:

b - See class javadoc

f - the inclusion probability used to produce the set with size a.

Returns:

the approximate lower bound