<p>+1 to @NickCox.  He has done an especially good job of talking about edits to questions, let me add that I think that goes double for answers.  As it happens, this same issue occurred yesterday with a very well-meaning user making changes to an old answer to correct what he thought were simple, innocuous mistakes on the part of the answerer.  In fact, he turned out to have been right, but I believe as a general policy it should be left to the answerer to make those changes at their discretion.  Here are my key positions:  </p>

<ul>
<li>Do not edit someone else's answer to change what you disagree with.  This is not the proper use of edits.  Leave a comment and/or downvote.  The answerer can respond, and make changes or not as they choose, but either way future readers will be made aware of the issue.</li>
<li>Even if it is factually untrue, do not edit to change errors.  Leave comments to ask the answerer for clarification / to point out the error.  If you feel strongly enough, you can downvote; you don't have to downvote, I rarely do.  It is just your strongest option.  </li>
<li>Personally, I would probably not edit to make such changes even if nothing happened for a long period of time.  </li>
<li>Although we may edit to correct, e.g., typos, typos are small things like spelling errors, not factual claims.  "Build" instead of <em>built</em> is a typo. The distinction (probably) has no epistemic content in the context of a given answer.  Claiming a statistical model has a property is a factual claim.  We should let the factual claims of the answer remain as the author intended them.  I think it is for the answerer to clarify them.  My position is that we should not edit an answer to change a substantive claim.  </li>
<li>I acknowledge that I have something of a double standard on editing: I feel fairly free to edit questions, but am quite reluctant to edit answers.  I only make superficial edits to answers, but often make substantive edits to questions when they are statistically confused and/or not clear English.  (However, I do not make changes outside of what I think the OP is trying to ask, and I typically leave a comment to the OP to make sure it still says what they want it to say.)  </li>
<li>Adding your own answer is another good option.  </li>
</ul>

<p>Another suggestion in this thread is to delete answers that do not fit.  I disagree with this also.  I recently addressed this issue on meta.CV here: <a href="https://stats.meta.stackexchange.com/a/2265/7290">When should answers be self-deleted?</a>  (I should also note that asking moderators to delete answers that do not fit can also be dangerous, see: <a href="https://stats.meta.stackexchange.com/q/2284/7290">Why was an answer considered off topic and when was it deleted?</a>)  Although I do not have a problem with deleting non-answers (new questions, comments, spam, etc.), I think something that was intended as an answer (even if under a mistaken reading of the question) should be allowed to stay.  In short, answers should not be deleted for being incorrect (or in this case not fitting well).  As above, I think the proper remedies are to comment, downvote, or add another answer of your own.  </p>
