/**
  * Check if the IDs of all possible owners match on the quizzes
  * and person creating/who created the AB Test
  * @param $ab_test_owner_id (int/string) ID of the person creating/who created the ab_test
  * @param $quiz_id_a (int/string) ID of Quiz A
  * @param $quiz_id_b (int/string) ID of Quiz B
  * @return $valid (BOOLEAN) true if OK, false if fails
  */
 protected function validate_ab_test_owner($ab_test_owner_id, $quiz_id_a, $quiz_id_b)
 {
     $valid = false;
     $quiz_a = new Enp_quiz_Quiz($quiz_id_a);
     $quiz_b = new Enp_quiz_Quiz($quiz_id_b);
     $quiz_a_owner = $quiz_a->get_quiz_owner();
     $quiz_b_owner = $quiz_b->get_quiz_owner();
     if ((int) $quiz_a_owner === (int) $quiz_b_owner && (int) $quiz_a_owner === (int) $ab_test_owner_id) {
         $valid = true;
     } else {
         $this->add_error('You are not the owner of one or more of the quizzes.');
     }
     return $valid;
 }