# oops...
while ( my $row = $sth1->fetchrow_arrayref() ) {
    my $calc_rank = $row->{ranker1} + $row->{ranker2};

    %ranked{ $row->{studentid} } = $calc_rank;
}

# should actually read
while ( my $row = $sth1->fetchrow_arrayref() ) {
    my $calc_rank = $row->[1] + $row->[2];

    %ranked{ $row->[0] } = $calc_rank;
}