<p><em>Copying my comment from above and slightly expanding:</em></p>

<p>We don't need a tag for success/failure in experiments (as we don't need tags like <code>[success]</code>, <code>[nobel-prize]</code>, <code>[failed-phd-and-left-academia]</code>, etc.). Apart from that, even if sometimes "failure" has some statistical meaning, it is too ambiguous as a tag name, and such a tag will inevitably be misused. I would say we should simply eliminate it altogether. Threads about survival analysis should be retagged as <a href="https://stats.stackexchange.com/questions/tagged/survival" class="post-tag" title="show questions tagged &#39;survival&#39;" rel="tag">survival</a>.</p>

<p>There are only 23 threads tagged with <a href="https://stats.stackexchange.com/questions/tagged/failure" class="post-tag" title="show questions tagged &#39;failure&#39;" rel="tag">failure</a>, so it's easy to get rid of it.</p>
