protected function is_dubious_question($questionstat) {
        if ($this->is_calculated_question_summary($questionstat)) {
            // We only care about the minimum value here.
            // If the minimum value is less than the threshold, then we know that there is at least one value below the threshold.
            list($discriminativeefficiency) = $questionstat->get_min_max_of('discriminativeefficiency');
        } else {
            $discriminativeefficiency = $questionstat->discriminativeefficiency;
        }

        if (!is_numeric($discriminativeefficiency)) {
            return false;
        }

        return $discriminativeefficiency < 15;
    }