 above):</p>
<ol>
<li><p>Model fitting techniques, which require selection of one or more complexity parameters, often provide routines based on cross-validation or similar to determine this parameter. If this routine is already at hand, the complexity function needed for the <code>peperr</code> call is not more than a wrapper around that, which consists of providing the data in the required way, calling the routine and return the selected complexity value(s).</p></li>
<li><p>For a given model fitting routi