TRUE)2:as.factor(cal_time)7  </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>                                                        2.854e-01  </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  poly(j, degree = poly_degree, raw = TRUE)3:as.factor(cal_time)7  </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>                                                        2.453e-04  </span>
<span class="r-out co"><span class="r-pr">#&gt;</span>  poly(j, degree = poly_degree