public Number getQ1Value(int series, int item);

    /**
     * Returns the Q3 median-value for the specified series and item.
     *
     * @param series  the series (zero-based index).
     * @param item  the item (zero-based index).
     *
     * @return The Q3 median-value for the specified series and item.
     */
    public Number getQ3Value(int series, int item);