00</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>     x_3        (a)    1.000                           </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>     x_4        (b)    0.752    0.038   19.760    0.000</span>
<span class="r-out co"><span class="r-pr">#&gt;</span> </span>
<span class="r-out co"><span class="r-pr">#&gt;</span> Intercepts:</span>
<span class="r-out co"><span class="r-pr">#&gt;</span>                    Estimate  Std.Err  z-value  P(&gt;|z|)</span>
<span