0000493: FIXED: bug in Student t-tests

Viewing Issue Advanced Details [ Jump to Notes ]

[ View Simple ] [ Issue History ] [ Print ]

Category

Severity

Reproducibility

Date Submitted

Last Update

0000493

[ALGLIB] Statistics

minor

always

2012-11-07 17:14

2012-11-21 16:38

Reporter

karuzo

View Status

public

Assigned To

SergeyB

Priority

normal

Resolution

fixed

Platform

Status

resolved

Projection

none

OS Version

ETA

none

Fixed in Version

3.7.0

Product Version

3.6.0

Target Version

3.7.0

Product Build

Summary

0000493: FIXED: bug in Student t-tests

Description

Issue fixed. studenttest1/studenttest2 now return correct values, depending on sign of difference between means of X and Y.

ORIGINAL MESSAGE:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
studenttest1 returns all p-value=1 when all values of sample X are equal and different from assumed Mean.

Similarly studenttest2 returns all p-value=1 when all values of sample X are equal and different from equal values of sample Y.

I suppose this is wrong, as rather all p-values should be zero.

Steps To Reproduce

Additional Information

Dim bt As Double, rt As Double, lt As Double
Call alglib.studentttest1({1, 1, 1, 1, 1}, 5, 0, bt, rt, lt)
Console.WriteLine("bothTails={0}, rightTail={1}, leftTail={2}", bt, rt, lt)
Call alglib.studentttest2({1, 1, 1, 1, 1}, 5, {2, 2, 2, 2, 2}, 5, bt, rt, lt)
Console.WriteLine("bothTails={0}, rightTail={1}, leftTail={2}", bt, rt, lt)

Output:
bothTails=1, rightTail=1, leftTail=1
bothTails=1, rightTail=1, leftTail=1

Programming language

Unspecified

Attached Files

Relationships

There are no notes attached to this issue.

Issue History
Date Modified	Username	Field	Change
2012-11-07 17:14	karuzo	New Issue
2012-11-07 17:14	karuzo	Programming language	=> Unspecified
2012-11-09 16:55	SergeyB	Status	new => assigned
2012-11-09 16:55	SergeyB	Assigned To	=> SergeyB
2012-11-09 16:56	SergeyB	Target Version	=> 3.7.0
2012-11-21 16:38	SergeyB	Description Updated
2012-11-21 16:38	SergeyB	Status	assigned => resolved
2012-11-21 16:38	SergeyB	Fixed in Version	=> 3.7.0
2012-11-21 16:38	SergeyB	Resolution	open => fixed
2012-11-21 16:38	SergeyB	Summary	Student tests returns all p-value=1 for equal-valued samples => FIXED: bug in Student t-tests

Mantis 1.1.6[^]