Which is measuring the result of a particular thread of conversation, which is not -quite- the same as judging whether or not the conversation should have been had to begin with. That would be substituting your posterior certainty of a particular claim for your prior certainty for all subsequent claims.
It's data, but you'd need a lot more of that kind of data in order to make claims with any kind of certainty about what your prior certainty should be going forward. There's also the question of whether that data would be collected at all if a particular line of conversation were productive.
In line with the results of the poll here, a thread for discussing politics. Incidentally, folks, I think downvoting the option you disagree with in a poll is generally considered poor form.
1.) Top-level comments should introduce arguments; responses should be responses to those arguments.
2.) Upvote and downvote based on whether or not you find an argument convincing in the context in which it was raised. This means if it's a good argument against the argument it is responding to, not whether or not there's a good/obvious counterargument to it; if you have a good counterargument, raise it. If it's a convincing argument, and the counterargument is also convincing, upvote both. If both arguments are unconvincing, downvote both.
3.) A single argument per comment would be ideal; as MixedNuts points out here, it's otherwise hard to distinguish between one good and one bad argument, which makes the upvoting/downvoting difficult to evaluate.
4.) In general try to avoid color politics; try to discuss political issues, rather than political parties, wherever possible.
If anybody thinks the rules should be dropped here, now that we're no longer conducting a test - I already dropped the upvoting/downvoting limits I tried, unsuccessfully, to put in - let me know. The first rule is the only one I think is strictly necessary.
Debiasing attempt: If you haven't yet read Politics is the Mindkiller, you should.