<p><em>Many of the good questions on DS.SE would be well-suited for CrossValidated</em>. The rest are either a) suited just fine for either StackOverflow or SciComp, or b) just plain bad questions anyway.</p>

<p>Fact (read: strong opinion) is, the data science site shouldn't exist as a separate entity. The way I see it, its existence can affect CrossValidated somewhere along a continuum between two outcomes:</p>

<ol>
<li><p>It could have a positive effect on CrossValidated by attracting more users to the StackExchange network who would have otherwise never signed up at all. These users might then sign up for CV and start contributing here. It would be especially positive if these users had somewhat different backgrounds from the existing CV user base and could offer a different and expanded range of expertise.</p></li>
<li><p>It could have a negative effect by dilution of CV's user base and concentration of CV's purview. This ties back to what I said above. It is entirely possible that every user who signs up for DS.SE is a user who would otherwise have signed up for CV, but now didn't. That potentially means fewer good questions and, of particular concern lately, fewer good answers from people that might have some real expertise to contribute. At the same time, the subject matter will also be split between CV and DS, making both sites less relevant, not to mention engendering confusion and duplication of question-answering effort (of which I suspect there is a limited maximum flow over time).</p></li>
</ol>

<p>The same two points could be made about StackOverflow, except that StackOverflow is a juggernaut and is far too big to be affected by anything other than its own half-decade of inertia. Indeed, the fact that it can coexist with Ubuntu, Linux, Programmers, ServerFault, Databases, Code Review, Theoretical CS, and a host of other specialized software-specific sites is a testament to this. CrossValidated is not StackOverflow.</p>

<p>Based on what I see over at DS, it has in fact attracted some new expertise, and I doubt that expertise has really been "poached" from CrossValidated's would-be user base. But the crossover has not happened, and I think this is to the detriment of both groups of users. The data scientists in academia and industry have already discovered that there has been an artificial gap between the computer scientists and the statisticians (and the economists and political scientists and sociologists and linguists and neuroscientists and business analysts and marketing researchers......). Over the last year they've rushed to close it, because mixing of expertise and exchange of ideas between two mature fields is possibly the best recipe for rapid advancement. The same benefits apply, I think, to a website that exists purely to facilitate the sharing of expertise.</p>

<p>As far as CV's rejection of "implementation" questions goes, I think SciComp will take care of that problem (and here's to its success) in the same way that Open Data should take care of our rejection of "dataset request" questions. DS questions are either statistics questions, programming questions, or numerical/high-performance computing questions. Those that fall under more than one category can be split up and asked piecemeal on different sites. That is how the rest of StackExchange works, it seems to work well, and I'm a big fan of the model. There is no reason why it can't be applied to handle a new breed of questions.</p>
