Manual Reference Pages - TEXT::NSP::MEASURES::2D::FISHER2::LEFT (3)
Text::NSP::Measures::2D::Fisher2::left - Perl module implementation of the left sided
Fishers exact test (Deprecated).
my $leftFisher = Text::NSP::Measures::2D::Fisher2::left->new();
my $npp = 60; my $n1p = 20; my $np1 = 20; my $n11 = 10;
$leftFisher_value = $leftFisher->calculateStatistic( n11=>$n11,
if( ($errorCode = $leftFisher->getErrorCode()))
print STDERR $erroCode." - ".$leftFisher->getErrorMessage();
print $leftFisher->getStatisticName."value for bigram is ".$leftFisher_value;
This module provides a naive implementation of the fishers left
sided exact tests. That is the implementation does not have any
optimizations for performance. This will compute the factorials and
the hypergeometric measures using direct multiplications.
This measure should be used if you need exact values without any
rounding errors, and you are not worried about the performance of
the measure, otherwise use the implementations under the
Text::NSP::Measures::2D::Fisher module. To use this implementation,
you will have to specify the entire module name. Usage:
statistic.pl Text::NSP::Measures::Fisher2::left dest.txt source.cnt
Assume that the frequency count data associated with a bigram
<word1><word2> is stored in a 2x2 contingency table:
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
A left sided test is calculated by adding the probabilities of all
the possible two by two contingency tables formed by fixing the
marginal totals and changing the value of n11 to less than the given
value. A left sided Fishers Exact Test tells us how likely it is to
randomly sample a table where n11 is less than observed. In other words,
it tells us how likely it is to sample an observation where the two words
are less dependent than currently observed.
calculateStatistic() - This method computes the left sided Fishers exact test.
INPUT PARAMS : $count_values .. Reference of an array containing
the count values computed by the
RETURN VALUES : $left .. Left Fisher value.
getStatisticName() - Returns the name of this statistic
INPUT PARAMS : none
RETURN VALUES : $name .. Name of the measure.
Ted Pedersen, University of Minnesota Duluth
Satanjeev Banerjee, Carnegie Mellon University
Amruta Purandare, University of Pittsburgh
Bridget Thomson-McInnes, University of Minnesota Twin Cities
Saiyam Kohli, University of Minnesota Duluth
Last updated: $Id: left.pm,v 1.10 2008/03/26 17:24:15 tpederse Exp $
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
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 v5.20.3 ||TEXT::NSP::MEASURES::2D::FISHER2::LEFT (3) ||2008-03-26 |
Visit the GSP FreeBSD Man Page Interface.
Output converted with manServer 1.07.