<p>I think there's a mix of things but I'll mention a few motivations:</p>

<p>1) being known in the places I work/have worked as someone who knows a fair bit of statistics means I spend/spent a lot of time answering statistics questions <em>anyway</em>. At least for the common questions, I can instead point people here - and in the place of answering those questions, carry my share by providing answers here too.</p>

<p>2) I particularly like the idea of a searchable, permanent repository of questions and answers, especially one where the questions get edited and clarified and the answers often improve over time - it means when I come up with a good answer, <em>it doesn't just 'die' when I finish solving one person's problem</em>, like it tends to when someone asks me a question in person. The combination of convenience and permanence makes it worthwhile to come back and clarify a paragraph in response to a followup comment, or add some clarifying picture, or generalize an answer slightly so it also answers another question, or covers the question in a way the asker mightn't have even understood enough to ask. </p>

<p>And I find that my better answers, ones I have crafted and reworked, tend to influence the way I write my explanations elsewhere. My written explanations of concepts slowly improve.</p>

<p>3) I learn from just reading other answers, and from answering questions myself (checking details in a paper or running a quick analysis or simulation I don't normally do changes a lot of stuff I <em>sort of</em> know into stuff I actually know). I may have been a statistician for a long time, but there's still plenty I don't know, or don't know as well as I should. Among other things, it's a neat way to learn about things <em>I didn't know</em> I didn't know.</p>

<p>4) I like that there's an opportunity for <em>me</em> to ask questions, should I need it - and the bigger the community gets, the more value it's likely to have for me.</p>

<p>5) When I get bored, spending 10 or even 20 minutes writing an answer is notionally more rewarding than getting another coffee.</p>

<p>6) If you like statistics, it's just interesting, you know? A reasonable fraction of the questions are simply fun to think about.</p>
