private function setQuestionHidden($iQid)
 {
     $oQuestion = Question::model()->find("sid=:sid AND qid=:qid", array(":sid" => $this->iSurveyId, ":qid" => $iQid));
     if (!$oQuestion) {
         return;
     }
     $oAttribute = QuestionAttribute::model()->find("qid=:qid AND attribute='hidden'", array(":qid" => $iQid));
     if (!$oAttribute) {
         $oAttribute = new QuestionAttribute();
         $oAttribute->qid = $iQid;
         $oAttribute->attribute = "hidden";
     }
     $oAttribute->value = 1;
     if ($oAttribute->save()) {
         return true;
     } else {
         $this->addResult("Unable to set {$iQid} hidden", 'error', $oAttribute->getErrors());
     }
 }