<h3>Web archive</h3>
<p>These links seem to have been in place at least since October 2020, at least one and a half year ago.</p>
<p>We can see this in the following archived webpage which contains the link <code>http://www.fharrell.com/p/blog-page.html</code></p>
<p><a href="https://web.archive.org/web/20201020171335/https://stats.stackexchange.com/questions/266670/how-often-should-a-statistical-model-lets-say-logistic-regression-be-evaluated" rel="nofollow noreferrer">https://web.archive.org/web/20201020171335/https://stats.stackexchange.com/questions/266670/how-often-should-a-statistical-model-lets-say-logistic-regression-be-evaluated</a></p>
<hr />
<h3>Stackexchange dump</h3>
<p>It is possible to dig further by using the database dump from stack exchange.</p>
<p>It seems very unlikely that the system can change the body text without leaving a trace in the post history. That history can already be viewed via the website and there is no trace in the history like user 'community' editing some link or style.</p>
<p>Anyway, if there would be such a change that did not show up in the post history then it should be still possible to see it in the database dumps. Because I have currently no access to my laptop, I can not perform that search.</p>
<hr />
<h3>Potential explanation</h3>
<p>The web address ending with <code>/p/blog-page.html</code> is not so strange. It might stem from the blogspot webpage: <a href="https://feharrell.blogspot.com/p/blog-page.html" rel="nofollow noreferrer">https://feharrell.blogspot.com/p/blog-page.html</a></p>
<p>It could be possible that you wrongly combined two url's. This might explain why, as Whuber mentioned in the comments, only posts from 2017 have the error.</p>
<hr />
<h3>Other occurances (and potential explanation 2)</h3>
<p>The link also occurs in comments</p>
<p><a href="https://stats.stackexchange.com/questions/287362/analysis-of-variance-for-binary-data#comment549971_287363">Analysis of variance for binary data</a></p>
<blockquote>
<p>Some intuitive and simple approaches are discussed in BBR Chapter 16 - see link at fharrell.com/p/blog-page.html</p>
</blockquote>
<p>And on twitter</p>
<p><a href="https://mobile.twitter.com/5_utr/status/1497980771432386563" rel="nofollow noreferrer">https://mobile.twitter.com/5_utr/status/1497980771432386563</a></p>
<blockquote>
<p>Clinical trialists: please quit computing change from baseline. See BBR Chapter 14: <a href="http://fharrell.com/p/blog-page.html" rel="nofollow noreferrer">http://fharrell.com/p/blog-page.html</a></p>
</blockquote>
<p>On twitter it seems that also others have linked to the broken links:</p>
<p><a href="https://i.stack.imgur.com/NmAH5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NmAH5.png" alt="search on twitter" /></a></p>
<p>I can't search this easily because I don't have a Twitter account and that makes Twitter evil towards me when I try to search it's pages. But anyway, those references might indicate that possibly you were using your website in a different mode with different links around 2017.</p>
<p>And yes indeed, the page <code>https://www.fharrell.com/p/blog-page.html</code> used to exist back in 2017. Or at least, the internet archive seems to agree with me. This page can be found in the archives</p>
<ul>
<li><p>On 27 December 2017 it looked like this: <a href="https://web.archive.org/web/20171227182433/http://www.fharrell.com/p/blog-page.html" rel="nofollow noreferrer">https://web.archive.org/web/20171227182433/http://www.fharrell.com/p/blog-page.html</a></p>
</li>
<li><p>On 18 January 2018 it was a 'page does not exist' webpage: <a href="https://web.archive.org/web/20180118062901/http://www.fharrell.com/p/blog-page.html" rel="nofollow noreferrer">https://web.archive.org/web/20180118062901/http://www.fharrell.com/p/blog-page.html</a></p>
</li>
</ul>
