public function corrEmployment($level, $levelid = null)
 {
     $rateEmployment = [];
     $attrition = [];
     $batches = [];
     $results = Correlation::getEmployment($level, $levelid);
     foreach ($results as $result) {
         array_push($batches, $result->batch);
         $rateEmployment[$result->batch] = $result->ratio;
         $attrition[$result->batch] = $result->dropouts;
     }
     return round($this->getCorrelation($rateEmployment, $attrition, $batches), 2);
 }