<p>I don't think question length alone is the key. If I was trying to model the likelihood of response, I would include measures of question length, question complexity and question novelty, together with their interactions (at least 2 way), along with question answerability.</p>

<p>I don't know of objective ways to measure complexity or novelty of questions.</p>

<p>But some complex questions <em>demand</em> a long question.  Also, if the question involves code, it's nice to see the code. Very short questions cannot possibly include context, but context is often key. </p>

<p>And, while I am probably more toward the "keep" than "close" end of the continuum on question novelty, it is tiresome (and unproductive) to answer a question that has been asked already in the same way. </p>
