<p>I occasionally see reasonable questions get deleted by their authors after being closed as duplicates. Here's one recent example:</p>
<p><a href="https://stats.stackexchange.com/questions/588900/does-fixed-effect-and-mixed-effect-model-have-same-prediction">https://stats.stackexchange.com/questions/588900/does-fixed-effect-and-mixed-effect-model-have-same-prediction</a></p>
<p>It seems to me that this undermines the value of the close-as-duplicate system; having linked questions makes finding good answers here easier - and probably via google too.</p>
<p><strong>Is this a situation in which voting to undelete the question is acceptable and a good idea?</strong> I'm aware of the conditions in which we <em>can</em>, but I've not seen much advice about when we <em>should</em>.</p>
<p>I'm also aware that authors cannot delete their question if it</p>
<blockquote>
<ul>
<li>has an answer with upvotes (even if that answer has a net zero or negative score)</li>
<li>has an accepted answer</li>
<li>has multiple answers (even if there are no upvotes)</li>
<li>has an answer with an awarded bounty</li>
<li>has at least one other question that is marked as a duplicate of your    question</li>
</ul>
</blockquote>
<p>The quoted text above is from  <a href="https://meta.stackexchange.com/questions/5221/how-does-deleting-work-what-can-cause-a-post-to-be-deleted-and-what-does-that">How does deleting work? What can cause a post to be deleted, and what does that actually mean? What are the criteria for deletion?</a></p>
