File Coverage

blib/lib/Statistics/LogRank.pm

Criterion	Covered	Total	%
statement	54	58	93.1
branch	3	6	50.0
condition	1	3	33.3
subroutine	6	6	100.0
pod	0	3	0.0
total	64	76	84.2

package Statistics::LogRank;

$VERSION = '0.03';

use strict;
use Carp;
use Statistics::Distributions;

##############
sub new
{
    my $proto = shift;
    my $class = ref($proto) || $proto;
    my $self= {};

    bless($self,$class);
    return $self;
}
##############

##############
sub load_data {
    my $self = shift;
    my $sample_name = shift;

    my (@sample_data)=@_;

    $self->{sample_data}->{$sample_name}=\@sample_data;

    return $self;
} # end sub load_data
##############

##############
sub perform_log_rank_test {
    my $self=shift;

    my ($first_survive_name,$first_fail_name,$second_survive_name,$second_fail_name)=@_;

    my (@e,@d,@v);
    my ($N1,$D,$N2,$N);

    my $count=0;
    while ($count < @{$self->{sample_data}->{$first_survive_name}})
    {
	$N1 = ${$self->{sample_data}->{$first_survive_name}}[$count];

        $D = ${$self->{sample_data}->{$first_fail_name}}[$count] + ${$self->{sample_data}->{$second_fail_name}}[$count];

        $N2 = ${$self->{sample_data}->{$second_survive_name}}[$count];

        $N = $N1 + $N2;

        if ($N1 + $N2 == 0) {$e[$count]=0;}
        else {$e[$count] =  $N1 * $D / ( $N1 + $N2);}
        $d[$count] = ${$self->{sample_data}->{$first_fail_name}}[$count] - $e[$count];
        if (($N**2 * ($N-1))==0) {$v[$count]=0;}
        else {$v[$count] = ($N1 * $N2 * $D *($N - $D)) / ($N**2 * ($N-1));}

	$count++;
    } # end while


my $total_e=0;
my $total_d=0;
my $total_v=0;

    my $count=0;
    while ($count < @{$self->{sample_data}->{$first_survive_name}})
    {
	$total_e += $e[$count];
	$total_d += $d[$count];
	$total_v += $v[$count];
	$count++
    }

if ($total_v ==0) {$total_v = 0.000000000001;}

my $log_rank_statistic = $total_d**2 / $total_v;
my $chi_prob=Statistics::Distributions::chisqrprob (1,$log_rank_statistic);

return ($log_rank_statistic,$chi_prob);
} # end sub perform_log_rank_test
##############
1;

__END__