<p>The <a href="https://stats.stackexchange.com/help/editing">help on editing</a> lists some circumstances in which it's okay to edit posts (i.e. questions and answers). These include:</p>

<ul>
<li>To fix grammar and spelling mistakes  </li>
<li>To clarify the meaning of the post (without changing that meaning) </li>
</ul>

<p>The first suggests that typos should probably be fixed, and the second clarifies that we must be careful to preserve the <em>intent</em>.</p>

<p>In this specific case, the intent was pretty obvious, and I think it's an error of the same kind as a 1-letter typo that results in a completely different word which results in a grammatically possible but plainly unintended meaning - the error is minor (the intent being correct aside from a typo), but a naive reading would be grossly misleading. Generally it's better if the person posting the answer fixes it, but if that may not happen for a long time (or at all), it would seem to be better to edit in spite of the limitation.</p>

<p>While one-letter corrections are to be avoided, where a naive reader would be likely to be misled, and the OP isn't likely to change it soon, I think an edit is okay, and indeed, in keeping with the sense I get from the guidelines in the help ... but I think it's incumbent on us to carefully label the reason for the change when making the edit, and generally, to highlight the change in comments.</p>

<p>I think this is broadly consistent with the help.</p>
