Text::NSP::Measures::2D::odds - Perl module to compute the Odds ratio for bigrams.
use Text::NSP::Measures::2D::odds; my $npp = 60; my $n1p = 20; my $np1 = 20; my $n11 = 10; $odds_value = calculateStatistic( n11=>$n11, n1p=>$n1p, np1=>$np1, npp=>$npp); if( ($errorCode = getErrorCode())) { print STDERR $errorCode." - ".getErrorMessage()."\n""; } else { print getStatisticName."value for bigram is ".$odds_value."\n""; }
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 odds ratio computes the ratio of the number of times that the words in a bigram occur together (or not at all) to the number of times the words occur individually. It is the cross product of the diagonal and the off-diagonal.
Thus, ODDS RATIO = n11*n22/n21*n12
if n21 and/or n12 is 0, then each zero value is "smoothed" to one to avoid a zero in the denominator.
INPUT PARAMS : $count_values .. Reference of an hash containing the count values computed by the count.pl program.
RETURN VALUES : $odds .. Odds ratio for this bigram.
INPUT PARAMS : none
RETURN VALUES : $name .. Name of the measure.
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>
Last updated: $Id: odds.pm,v 1.18 2006/06/21 11:10:52 saiyam_kohli Exp $
@inproceedings{ blaheta01unsupervised, author = {D. BLAHETA and M. JOHNSON}, title = {Unsupervised learning of multi-word verbs}, booktitle = {}Proceedings of the 39th Annual Meeting of the ACL}, year = {2001}, pages = {54-60}, url = L<http://www.cog.brown.edu/~mj/papers/2001/dpb-colloc01.pdf> }
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
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