t>
<dd><p>Numeric vector of centers for binning. Use <code>bin = "centers"</code>, if supplying centers.</p></dd>


<dt>breaks</dt>
<dd><p>Numeric vector of breaks for binning. Use <code>bin = "breaks"</code>, if supplying breaks.</p></dd>


<dt>nbins</dt>
<dd><p>Numeric number indicating the number of bins to use.</p></dd>


<dt>altx</dt>
<dd><p>Unquoted variable name in observed data for alternative x-variable binning.</p></dd>


<dt>stratum</dt>
<dd><p>List indicating the name of stratification variable 