<p>I want to discuss the following three tags:  <a href="https://stats.stackexchange.com/questions/tagged/mixed-model" class="post-tag" title="show questions tagged &#39;mixed-model&#39;" rel="tag">mixed-model</a> (2000+), <a href="https://stats.stackexchange.com/questions/tagged/random-effects-model" class="post-tag" title="show questions tagged &#39;random-effects-model&#39;" rel="tag">random-effects-model</a> (580) and <a href="https://stats.stackexchange.com/questions/tagged/fixed-effects-model" class="post-tag" title="show questions tagged &#39;fixed-effects-model&#39;" rel="tag">fixed-effects-model</a> (400).</p>

<p>There is a well-known terminological ambiguity between econometrics and other statistics with regards to the "random effects" and "fixed effects". <strong>I feel that our tags <em>add</em> to this ambiguity, instead of clearing it up.</strong></p>

<ul>
<li><p>Mixed models are linear models that include random effects and fixed effects, i.e. random factors and fixed factors (or, rarely, only random factors). <strike>The terms "random/fixed effects model" are never (?) used to refer to mixed models.</strike> Update: Mixed models are also sometimes called "random effects models".</p></li>
<li><p>In econometrics, a "fixed effects model" is a way to treat panel data which is equivalent to a standard linear model with only fixed effects. In contrast, a "random effects model" is a way to treat panel data which is formally equivalent to a mixed model with a random intercept but which is estimated via FGLS and not via MLE (as mixed models are). (Evidence: <a href="https://stats.meta.stackexchange.com/questions/1369">@StasK's 2012 Meta answer</a> and my recent <a href="https://stats.stackexchange.com/questions/238214">question on the main site</a>.)</p></li>
</ul>

<p>So conceptually <code>[fixed-effects-model]</code> tag should only be applied to questions about econometrics; in practice people often use it on questions about mixed models to refer to fixed effects. <strong>This is confusing.</strong> And  <code>[random-effects-model]</code> tag can be, and is being used to refer to both, mixed models and random effects models in the econometrics sense. <strong>So the mixed models questions get split between these two tags, which is very unfortunate.</strong></p>

<p>What could be the ideal arrangement?</p>

<p>I'd say: rename these two tags such that they unambiguously refer to econometrics. For example: <code>[panel-random-effects]</code> and <code>[panel-fixed-effects]</code> (the word "econometrics" is too long to include in a tag name). And sort out the mixed models questions into <code>[mixed-model]</code>.</p>
