public function RAdjusted($r2, $predictors, $sample_size)
    {
        if( ($sample_size - $predictors - 1) != 0 ) {
            $radjusted = 1 - ((1 - $r2) * ($sample_size - 1)) / ($sample_size - $predictors - 1);
        } else {
            $radjusted = 1.0;
        }

        return $radjusted;
    }