public function dropdown_list() {
		$groups = array();

		$conditions_by_group = $this->get_conditions_by_group();

		foreach ( $conditions_by_group as $group => $_conditions ) {

			$conditions = array();

			foreach ( $_conditions as $id => $condition ) {
				$conditions[ $id ] = $condition['name'];
			}

			$groups[ $group ] = $conditions;
		}

		return $groups;
	}