I'll give you RTT mdev*. BTW, I've also changed the output to show 3 decimal places.

#!/bin/env perl
use strict;
use warnings;
use Getopt::Long;
use Net::Ping;

my $host;
my $count = 5;
my $interval = 1;
my $packetsize = 64; # remember that header data will be added to this
my $timeout = 5; # 5 is the default in Net::Ping

GetOptions(
    "h|host=s",             \$host,
    "c|count=i",            \$count,
    "i|interval=i",         \$interval,
    "s|packetsize=i",       \$packetsize,
    "W|timeout=i",          \$timeout, # you had w|allowableTime but t
+his makes more sense to me
);

die "$0: No host given!\n" unless ( defined $host );

my $p = Net::Ping->new( 
    'tcp', # BUG: Should be able to change this with a command line op
+tion
    $timeout,
    $packetsize,
);
$p->hires();

my %stats = ( received => 0, tsum => 0, tsum2 => 0, max => 0, min => 9
+999999999 );

for ( 1 .. $count ) 
{ 
    my ( $ret, $duration, $ip ) = $p->ping( $host );
    if ( $ret )
    {
        $duration *= 1000;
        $stats{received}++;
        $stats{min} = $duration if ( $duration < $stats{min} );
        $stats{max} = $duration if ( $duration > $stats{max} );
        $stats{tsum} += $duration;
        $stats{tsum2} += $duration * $duration;
        printf "Your RTT is %.3f ms\n", $duration;
    }
    sleep $interval if ( defined $interval && $interval > 0 );
}
if ( $stats{received} > 0 )
{
    $stats{avg} = $stats{tsum} / $stats{received};
    $stats{avg2} = $stats{tsum2} / $stats{received};
    $stats{mdev} = sqrt( $stats{avg2} - $stats{avg} * $stats{avg} );
}
$stats{loss} = ( $count - $stats{received} ) / $count * 100;
print "--- $host ping statistics ---\n";
printf "%d packets transmitted, %d received, %d%% packet loss\n", $cou
+nt, $stats{received}, $stats{loss};
printf "rtt min/avg/max/mdev = %.3f/%.3f/%.3f/%.3f ms\n", $stats{min},
+ $stats{avg}, $stats{max}, $stats{mdev} if $stats{received} > 0;
[download]

Update: I'm not giving you TTL because Net::Ping does not provide that information. Stick to what you are using if you really need this info.

* Source: http://serverfault.com/a/333203/67820

Thank you very much