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440 440
441# Autoload methods go after =cut, and are processed by the autosplit program. 441# Autoload methods go after =cut, and are processed by the autosplit program.
442 442
4431; 4431;
444__END__ 444__END__
445
445# Below is the stub of documentation for your module. You better edit it! 446# Below is the stub of documentation for your module.
446 447
447=head1 NAME 448=head1 NAME
448 449
449Statistics::Distributions - Perl module for calculating critical values of common statistical distributions 450Statistics::Distributions - Perl module for calculating probabilities and critical values of common statistical distributions
450 451
451=head1 SYNOPSIS 452=head1 SYNOPSIS
452 453
453 use Statistics::Distributions; 454 use Statistics::Distributions;
455
456 $uprob=uprob(-0.85);
457 print "upper probability of the u distribution: Q(u) = 1-G(u) (u=1.43) = $uprob";
458
459 $tprob=tprob(3, 6.251);
460 print "upper probability of the t distribution: Q = 1-G (3 degrees of freedom , t = 6.251) = $tprob";
461
462 $chisprob=chisqrprob(3, 6.25);
463 print "upper probability of the chi-square distribution: Q = 1-G (3 degrees of freedom, chi-squared = 6.25) = $chisprob";
464
465 $fprob=fprob(3,5, .625);
466 print "upper probability of the F distribution: Q = 1-G (3 degrees of freedom in numerator, 5 degrees of freedom in denominator, F $
467
468 $u=udistr(.05);
469 print "u-crit (95th percentile = 0.05 level) = $u";
470
471 $t=tdistr(1, .005);
472 print "t-crit (1 degree of freedom, 99.5th percentile = 0.005 level) =$t";
454 473
455 $chis=chisqrdistr(2, .05); 474 $chis=chisqrdistr(2, .05);
456 print "Chi-squared-crit (2 degrees of freedom, 95th percentile = 0.05 level) = $chis"; 475 print "Chi-squared-crit (2 degrees of freedom, 95th percentile = 0.05 level) = $chis";
457 476
458 $u=udistr(.05);
459 print "u-crit (95th percentile = 0.05 level) = $u";
460
461 $t=tdistr(1, .005);
462 print "t-crit (1 degree of freedom, 99.5th percentile = 0.005 level) =$t";
463
464 $f=fdistr(1,3, .01); 477 $f=fdistr(1,3, .01);
465 print "F-crit (1 degree of freedom in numerator, 3 degrees of freedom in denominator, 99th percentile = 0.01 level) = $f"; 478 print "F-crit (1 degree of freedom in numerator, 3 degrees of freedom in denominator, 99th percentile = 0.01 level) = $f";
466
467 $uprob=uprob(-0.85);
468 print "upper probability of the u distribution: Q(u) = 1-G(u) (u=1.43) = $uprob";
469
470 $chisprob=chisqrprob(3, 6.25);
471 print "upper probability of the chi-square distribution: Q = 1-G (3 degrees of freedom, chi-squared = 6.25) = $chisprob";
472
473 $tprob=tprob(3, 6.251);
474 print "upper probability of the t distribution: Q = 1-G (3 degrees of freedom , t = 6.251) = $tprob";
475 Note: this function works OK if t is close to 0, but is not accurate for if t is far from 0.
476
477 $fprob=fprob(3,5, .625);
478 print "upper probability of the F distribution: Q = 1-G (3 degrees of freedom in numerator, 5 degrees of freedom in denominator, F = 6.25) = $fprob";
479 479
480=head1 DESCRIPTION 480=head1 DESCRIPTION
481 481
482This Perl module calulates percentage points (6 significant digits) of the u (standard normal) distribution, 482This Perl module calulates percentage points (6 significant digits) of the u (standard normal) distribution,
483the student's t distribution, the chi-square distribution and the F distribution. 483the student's t distribution, the chi-square distribution and the F distribution.
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