ied Poisson model for negative binomial data ----------</span></span></span>
<span class="r-in"><span></span></span>
<span class="r-in"><span><span class="co"># ... following Section 5.1 of the "Object-Oriented Computation of Sandwich</span></span></span>
<span class="r-in"><span><span class="co"># Estimators" vignette of the sandwich package</span></span></span>
<span class="r-in"><span><span class="co"># https://cran.r-project.org/web/packages/sandwich/vignettes/sandwich-OOP.pdf</span></span></span>
<span