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Text::NSP::Measures::3UserIContributed Perl DocuText::NSP::Measures::3D::MI(3)

NAME
       Text::NSP::Measures::3D::MI - Perl module that provides error checks
       and
				     framework to implement Loglikelihood,
				     Total Mutual Information, Pointwise
       Mutual
				     Information and Poisson Stirling Measure
				     for trigrams.

SYNOPSIS
       Basic Usage

	 use Text::NSP::Measures::3D::MI::ll;

	 $ll_value = calculateStatistic( n111=>10,
					 n1pp=>40,
					 np1p=>45,
					 npp1=>42,
					 n11p=>20,
					 n1p1=>23,
					 np11=>21,
					 nppp=>100);

	 if( ($errorCode = getErrorCode()))
	 {
	   print STDERR	$erroCode." - ".getErrorMessage()."\n";
	 }
	 else
	 {
	   print getStatisticName."value for trigram is	".$ll_value."\n";
	 }

DESCRIPTION
       This module is the base class for the Loglikelihood and the True	Mutual
       Information measures. All these measure are similar. This module
       provides	error checks specific for these	measures, it also implements
       the computations	that are common	to these measures.

       Log-Likelihood measure is computed as
	    Log-Likelihood = 2 * [n111 * log(n111/m111)	+ n112 * log(n112/m112)	+
		      n121 * log(n121/m121) + n122 * log(n122/m122) +
		      n211 * log(n211/m211) + n212 * log(n212/m212) +
		      n221 * log(n221/m221) + n222 * log(n222/m222)]

       Total Mutual Information
	   tmi = [n111/nppp * log(n111/m111) + n112/nppp * log(n112/m112) +
		   n121/nppp * log(n121/m121) +	n122/nppp * log(n122/m122) +
		   n211/nppp * log(n211/m211) +	n212/nppp * log(n212/m212) +
		   n221/nppp * log(n221/m221) +	n222/nppp * log(n222/m222)]

       Pointwise Mutual	Information
	   pmi =   log (n111/m111)

       Poisson Stirling	Measure
	   ps =	n111 * ( log(n111/m111)	- 1)

       All these methods use the ratio of the observed values to expected
       values, for computations, and thus have common error checks, so they
       have been grouped together.

   Methods
       getValues($count_values)	- This method calls computeMarginalTotals the
       computeObservedValues() and the computeExpectedValues() methods to
       compute the observed and	expected values. It checks these values	for
       any errors that might cause the Loglikelihood, TMI and PMI measures to
       fail.
	   INPUT PARAMS	 : $count_values	   .. Reference	of an hash
	   containing
						      the count	values
	   computed by the
						      count.pl program.

	   RETURN VALUES : 1/undef	     ..returns '1' to indicate success
					       and an undefined(NULL) value to
	   indicate
					       failure.

       computePMI($n, $m) - Computes the pmi of	a given	observed and expected
       value pair.
	   INPUT PARAMS	 : $n	    ..Observed value
			   $m	    ..Expected value

	   RETURN VALUES : lognm   .. the log of the ratio of
				      observed value to	expected
				      value.

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
				    <bthomson@d.umn.edu>

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

HISTORY
       Last updated: $Id: MI.pm,v 1.16 2011/12/23 22:25:05 btmcinnes Exp $

BUGS
SEE ALSO
       <http://groups.yahoo.com/group/ngram/>

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

COPYRIGHT
       Copyright (C) 2000-2011,	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
       under the terms of the GNU General Public License as published by the
       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			  2011-12-23	Text::NSP::Measures::3D::MI(3)

NAME | SYNOPSIS | DESCRIPTION | AUTHOR | HISTORY | BUGS | SEE ALSO | COPYRIGHT

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