lass='op'>:</span><span class='fl'>3</span><span class='op'>]</span> <span class='op'>&lt;-</span> <span class='cn'>NA</span>

<span class='co'># for the 4PL item the estimated parameters are submitted, </span>
<span class='co'># for the GPCM items the lower asymptote = 0 </span>
<span class='co'># and the upper asymptote = 1.</span>
<span class='va'>la</span>     <span class='op'>&lt;-</span> <span class='fu'><a href='https://rdrr.io/r/base/c.html'>c</a></span><span class='op'>(</span><span class='fl'>0.02