# FreeBSD Manual Pages

```Text::NSP::Measures::2UseriContributed:Perl:Deasures::2D::Fisher::twotailed(3)

NAME
Text::NSP::Measures::2D::Fisher::twotailed - Perl module	implementation
of the two-sided
Fisher's exact test.

SYNOPSIS
Basic Usage

use Text::NSP::Measures::2D::Fisher::twotailed;

my \$npp = 60; my \$n1p = 20; my	\$np1 = 20;  my \$n11 = 10;

\$twotailed_value = calculateStatistic(	n11=>\$n11,
n1p=>\$n1p,
np1=>\$np1,
npp=>\$npp);

if( (\$errorCode = getErrorCode()))
{
print STDERR	\$errorCode." - ".getErrorMessage();
}
else
{
print getStatisticName."value for bigram is ".\$twotailed_value;
}

DESCRIPTION
Assume that the frequency count data associated with a bigram
<word1><word2> is stored	in a 2x2 contingency table:

word2	 ~word2
word1	  n11	   n12 | n1p
~word1	  n21	   n22 | n2p
--------------
np1	   np2	 npp

where n11 is the	number of times	<word1><word2> occur together, and n12
is the number of	times <word1> occurs with some word other than word2,
and n1p is the number of	times in total that word1 occurs as the	first
word in a bigram.

The fishers exact tests are calculated by fixing	the marginal totals
and computing the hypergeometric	probabilities for all the possible
contingency tables,

A twotailed fishers test	is calculated by adding	the probabilities of
all the contingency tables with probabilities less than the probability
of the observed table. The twotailed fishers test tells us how likely
it would	be to observe an contingency table which is less probable than
the current table.

Methods
calculateStatistic() - This method calculates the twotailed Fisher
value
INPUT PARAMS	 : \$count_values       .. Reference of an array
containing
the count values computed by
the
count.pl program.

RETURN VALUES : \$twotailed	       .. Twotailed Fisher value.

getStatisticName() - Returns the	name of	this statistic
INPUT PARAMS	 : none

RETURN VALUES : \$name      .. Name of the measure.

AUTHOR
Ted Pedersen,		    University of Minnesota Duluth
<tpederse@d.umn.edu>

Satanjeev Banerjee,	    Carnegie Mellon University
<satanjeev@cmu.edu>

Amruta Purandare,	    University of Pittsburgh
<amruta@cs.pitt.edu>

Bridget Thomson-McInnes,	    University of Minnesota Twin Cities
<bthompson@d.umn.edu>

Saiyam Kohli,		    University of Minnesota Duluth
<kohli003@d.umn.edu>

HISTORY
Last updated: \$Id: twotailed.pm,v 1.13 2008/03/26 17:21:19 tpederse Exp
\$

BUGS
@inproceedings{Pedersen96,
author	= {Pedersen, T.},
title = {Fishing For Exactness},
booktitle = {Proceedings of the South Central SAS User's
Group (SCSUG-96) Conference},
year =	{1996},
pages = {188--200},
month ={October},
url = L<http://www.d.umn.edu/~tpederse/pubs.html>}

<http://groups.yahoo.com/group/ngram/>

<http://www.d.umn.edu/~tpederse/nsp.html>

Copyright (C) 2000-2006,	Ted Pedersen, Satanjeev	Banerjee, Amruta
Purandare, Bridget Thomson-McInnes and Saiyam Kohli

This program is free software; you can redistribute it and/or modify it
Free Software Foundation; either	version	2 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A	PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received	a copy of the GNU General Public License along
with this program; if not, write	to

The Free Software Foundation, Inc.,
59 Temple Place - Suite 330,
Boston, MA  02111-1307, USA.

Note: a copy of the GNU General Public License is available on the web
at <http://www.gnu.org/licenses/gpl.txt>	and is included	in this
distribution as GPL.txt.

perl v5.32.0			 Text::NSP::Measures::2D::Fisher::twotailed(3)
```