/em>\(V\) is often only a rough approximation (and since the random effects structure may not fully capture all dependencies in the underlying true outcomes/effects), we can then apply cluster-robust inference methods (also known as robust variance estimation) to the model. This can be done with the <code><a href="robust.html">robust</a></code> function, which also interfaces with the improved inference methods implemented in the <a href="https://cran.r-project.org/package=clubSandwich" class="external-link