evel) linear models</h1>
<p>The package <code>HLMdiag</code> was created in order to provide a unified framework for analysts to diagnose hierarchical linear models (HLMs). When <code>HLMdiag</code> was created in 2014, it made diagnostic procedures available for HLMs that had not yet been implemented in statistical software. Over the past 6 years, other packages have gradually implemented some of these procedures; however, diagnosing a model still often requires multiple packages, each of which has its own