y), nrow(x)) -
      1$$.</p></td>
    </tr>
    <tr>
      <th>symmetric</th>
      <td><p>if <code>method</code> is <code>"symmetric"</code> then
    <code>symmetric</code> determines whether weights for \(R_0\) are
    symmetric and taken as the average of the row sums of <code>x</code> and
    <code>y</code> (<code>symmetric = TRUE</code>). If <code>symmetric = FALSE</code>
    (default) then the weights \(R_0\) are taken as the row sums of <code>y</code>
    unless user defined weights are provided via