ns for each group (i.e., Group 0 vs. Group 1). The sum of these numbers
should be equal to nperson. If NULL, the first half of the persons becomes Group 0 and the other half becomes Group 1.</p></td>
    </tr>
    <tr>
      <th>itemtype.size</th>
      <td><p>The number of items for each itemtype (i.e., itemtype 0 vs. itemtype 1). The sum of these numbers
should be equal to nitem. If NULL, the first half of the items becomes itemtype 0 and the other half becomes itemtype 1.</p></td>
    </tr>
    <tr>
    