>     instype_s1, lambexp, lnambx, totchr, vgood, year01</span>
<span class="r-msg co"><span class="r-pr">#&gt;</span> The following objects are masked from Mroz87 (pos = 12):</span>
<span class="r-msg co"><span class="r-pr">#&gt;</span> </span>
<span class="r-msg co"><span class="r-pr">#&gt;</span>     age, educ</span>
<span class="r-msg co"><span class="r-pr">#&gt;</span> The following objects are masked from MEPS2001 (pos = 13):</span>
<span class="r-msg co"><span class="r-pr">#&gt;</span> </span>
<span 