private static function validStats($type, $sub_type) {
    if ( ($type === 'content' && $sub_type === 'shortcode insert') || // Count number of shortcode inserts
         ($type === 'library' && $sub_type === NULL) || // Count number of times library is loaded in editor
         ($type === 'results' && $sub_type === 'content') ) { // Count number of times results page has been opened
      return TRUE;
    }
    elseif (self::isAction($type, $sub_type)) { // Count all actions
      return TRUE;
    }
    return FALSE;
  }