Cox model with different covariate</span></span></span>
<span class="r-in"><span><span class="va">cx</span> <span class="op">&lt;-</span> <span class="fu">coxph</span><span class="op">(</span><span class="fu">Surv</span><span class="op">(</span><span class="va">Tstart</span>,<span class="va">Tstop</span>,<span class="va">status</span><span class="op">)</span><span class="op">~</span><span class="va">x1.1</span><span class="op">+</span><span class="va">x2.2</span><span class="op">+</span><span class="fu">str