<p>I'd agree that there is at best a weak positive correlation. </p>

<p>But what is effort? It's not just the effort that went into an individual answer. The effort of following the forum over a few years needs to enter the accounting. So effort is obvious short-term effort $+$ whatever long-term effort is pertinent. </p>

<p>Over time on the forum, you learn at least subconsciously more about what the forum likes, as a collective set of preferences, and so learn a little about what works better. So, you get a little better at planning your effort. </p>

<p>Here is a very partial list, in no particular order, of what helps to get upvotes. (It should be no surprise in a statistical forum that the response of upvotes depends on several covariates.)  </p>

<ul>
<li><p>Writing clearly and fluently, with good command of English and strong self-editing, but also fairly concisely. </p></li>
<li><p>Graphs! For example, @Glen_b designs very clear, tasteful, customized graphs for many of his posts. </p></li>
<li><p>Some rigour and professionalism in analysis, wide sense. Even at a low level small details such as careful use of terminology and notation and mathematical typesetting help greatly. At a higher level, outstanding answers may use whatever mathematics it takes to get to the root of things. Here @whuber is among the masters. </p></li>
<li><p>Analyses of real data. Or simulations. In general, really good examples. </p></li>
<li><p>Some minor wackiness. Anything that evokes a wry smile. </p></li>
<li><p>Good lists of references. </p></li>
<li><p>Already having a fair reputation. It shouldn't be the case, as every answer should be up-voted only on its own merits, but having a good reputation for high-quality answers and forum maintenance attracts attention to your answers. </p></li>
<li><p>Multiple edits. Again, that in itself shouldn't be a reason for upvoting, but edits bump a thread to the top of the active list and draw attention thereby. </p></li>
</ul>

<p>Here are some of the things that don't help much: </p>

<ul>
<li><p>Rants. </p></li>
<li><p>Rather obvious riding of hobby-horses. </p></li>
<li><p>Marginal or limited relevance to the question. This is difficult to manage. Sometimes a poor question can be steered gently but firmly in a different good direction that finds the pearl amid the grit, and that's all positive (except possibly for the poor OP). But anything looking like "That reminds me obliquely of this different thing" usually gets few upvotes (and occasionally gets flak), however good it might be as an answer to a different question. </p></li>
<li><p>Being sloppy. </p></li>
<li><p>Being wrong! </p></li>
</ul>
