<p>I noticed that we have <a href="https://stats.stackexchange.com/questions/tagged/mixed-design" class="post-tag" title="show questions tagged &#39;mixed-design&#39;" rel="tag">mixed-design</a>×63 tag that did not have any wiki excerpt. Many of the questions are about <a href="https://en.wikipedia.org/wiki/Mixed-design_analysis_of_variance" rel="nofollow noreferrer">https://en.wikipedia.org/wiki/Mixed-design_analysis_of_variance</a>, i.e. ANOVA analysis with between-subject and within-subject factors. But a noticeable fraction of the questions is about mixed models, or about something else entirely. And indeed the term "mixed design" refers to experimental design and so in a way is very broad, encompassing large fraction of the mixed model questions. I don't think this is a productive tag.</p>

<p>My suggestion is to go through all [mixed-design] Qs, remove the ones that are not about mixed ANOVA, then rename the tag into [mixed-anova], and then make it a synonym of <a href="https://stats.stackexchange.com/questions/tagged/anova" class="post-tag" title="show questions tagged &#39;anova&#39;" rel="tag">anova</a>. The idea is that in the end we have <a href="https://stats.stackexchange.com/questions/tagged/anova" class="post-tag" title="show questions tagged &#39;anova&#39;" rel="tag">anova</a> and <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>, and Qs about mixed ANOVA should go into [anova].</p>

<p>Alternatively, we <em>could</em> have <a href="https://stats.stackexchange.com/questions/tagged/mixed-anova" class="post-tag" title="show questions tagged &#39;mixed-anova&#39;" rel="tag">mixed-anova</a> as a separate tag, but currently there are <a href="https://stats.stackexchange.com/search?q=%5Banova%5D+mixed+is%3Aquestion+-%5Bmixed-design%5D">hundreds Qs</a> about mixed ANOVA not tagged as such, so I'd say it's too late.</p>

<p>An additional complication is that we also have a <a href="https://stats.stackexchange.com/questions/tagged/split-plot" class="post-tag" title="show questions tagged &#39;split-plot&#39;" rel="tag">split-plot</a>×53 tag which is basically the same thing, but is more of a niche terminology. My inclination would be to leave it as is. Current wiki excerpt:</p>

<blockquote>
  <p>An experimental design used in situations where one factor can be changed more easily than another one. It's also called "mixed design" because it involves between-subject (hard to change) and within-subject (aka repeated measures; easy to change) factors. </p>
</blockquote>

<p>PS. This is a continuation of <a href="https://stats.meta.stackexchange.com/questions/1970">Let us merge [mixed], [mixed-effect] and [mixed-model] tags</a>.</p>
