public Number getValue(int row, int column) {
        return getMeanValue(row, column);
    }

    /**
     * Returns the value for an item (for this dataset, the mean value is
     * returned).
     *
     * @param rowKey  the row key.
     * @param columnKey  the columnKey.
     *
     * @return The value (possibly <code>null</code>).
     */
    public Number getValue(Comparable rowKey, Comparable columnKey) {
        return getMeanValue(rowKey, columnKey);