NAME

       Statistics::Distributions - Perl module for calculating critical values and upper
       probabilities of common statistical distributions

SYNOPSIS

         use Statistics::Distributions;

         $chis=Statistics::Distributions::chisqrdistr (2,.05);
         print "Chi-squared-crit (2 degrees of freedom, 95th percentile "
              ."= 0.05 level) = $chis\n";

         $u=Statistics::Distributions::udistr (.05);
         print "u-crit (95th percentile = 0.05 level) = $u\n";

         $t=Statistics::Distributions::tdistr (1,.005);
         print "t-crit (1 degree of freedom, 99.5th percentile = 0.005 level) "
              ."= $t\n";

         $f=Statistics::Distributions::fdistr (1,3,.01);
         print "F-crit (1 degree of freedom in numerator, 3 degrees of freedom "
              ."in denominator, 99th percentile = 0.01 level) = $f\n";

         $uprob=Statistics::Distributions::uprob (-0.85);
         print "upper probability of the u distribution (u = -0.85): Q(u) "
              ."= 1-G(u) = $uprob\n";

         $chisprob=Statistics::Distributions::chisqrprob (3,6.25);
         print "upper probability of the chi-square distribution (3 degrees "
              ."of freedom, chi-squared = 6.25): Q = 1-G = $chisprob\n";

         $tprob=Statistics::Distributions::tprob (3,6.251);
         print "upper probability of the t distribution (3 degrees of "
              ."freedom, t = 6.251): Q = 1-G = $tprob\n";

         $fprob=Statistics::Distributions::fprob (3,5,.625);
         print "upper probability of the F distribution (3 degrees of freedom "
              ."in numerator, 5 degrees of freedom in denominator, F = 6.25): "
              ."Q = 1-G = $fprob\n";

DESCRIPTION

       This Perl module calculates percentage points (5 significant digits) of the u (standard
       normal) distribution, the student's t distribution, the chi-square distribution and the F
       distribution. It can also calculate the upper probability (5 significant digits) of the u
       (standard normal), the chi-square, the t and the F distribution.  These critical values
       are needed to perform statistical tests, like the u test, the t test, the F test and the
       chi-squared test, and to calculate confidence intervals.

       If you are interested in more precise algorithms you could look at:
        StatLib: http://lib.stat.cmu.edu/apstat/ ;
        Applied Statistics Algorithms by Griffiths, P. and Hill, I.D., Ellis Horwood: Chichester
       (1985)

BUGS

       This final version 1.02 has been released after more than one year without a bug report on
       the previous version 0.07.  Nevertheless, if you find any bugs or oddities, please do
       inform the author.

INSTALLATION

       See perlmodinstall for information and options on installing Perl modules.

AVAILABILITY

       The latest version of this module is available from the Distribution Perl Archive Network
       (CPAN). Please visit http://www.cpan.org/ to find a CPAN site near you or see
       http://www.cpan.org/authors/id/M/MI/MIKEK/ .

AUTHOR

       Michael Kospach <mike.perl@gmx.at>

       Nice formating, simplification and bug repair by Matthias Trautner Kromann <mtk@id.cbs.dk>

COPYRIGHT

       Copyright 2003 Michael Kospach. All rights reserved.

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

SEE ALSO

       Statistics::ChiSquare, Statistics::Table::t, Statistics::Table::F, perl(1).