 optional second (outer) x parameter, which should be a
factor.</p></dd>


<dt>x2shift</dt>
<dd><p>Amount to shift along x axis for each level of <code>x2var</code>. By
default the function will arrange each level of <code>x2var</code> side by side.</p></dd>


<dt>xlab</dt>
<dd><p>Title for the x axis</p></dd>


<dt>ylab</dt>
<dd><p>Title for the y axis</p></dd>


<dt>plab</dt>
<dd><p>Optional character vector of labels for p-values. These must
align with column names in <code>object@stats$pvals</code>.</p>