Since senatorial announcements of newfound support for gay marriage have gotten dull, the hot new trend in politics is to try and predict which senator will be next to come out into the open on the issue. Some, like the Washington Post's Sean Sullivan, made predictions based on their guts. But if we learned anything during 2012, it's that data always trumps gut calls. So we looked at the data.
We had three theories of what state characteristic might serve as a predictor that its senator was about to change his or her mind. The first was how Obama fared in the state last November, that there might be correlation between how Obama did electorally and the order in which senators declared support on the issue. The second was household income, that senators' shifts correlated to socioeconomics. And, finally, that the correlation was between the density of same-sex couples in a state.
Obama's margin of victory
A quick description of methodology is in order. The blue line on each chart below (pegged to the left axis) indicates (using data very helpfully compiled by the Post) the number of days between a senator's announcement of support and the first senator to make such an announcement: Barbara Boxer, in June 2006. (This isn't quite true; Ron Wyden announced in 1996, but that threw off the curve.) So the flat part at the right of the blue curve is the recent spate of announcements. We included both interactive and static versions of the charts because we wanted to include a trend line — that dashed red line in the second chart below. (For the truly curious, that line is a fifth-order polynomial.)