Nate Silver's Forecast Is Very Optimistic About Same-Sex Marriage
After November's presidential election, the bossman at the New York Times' FiveThirtyEight blog became best known for correctly predicting the electoral outcomes of all 50 states. His forecast models became legendary.
Of course, he had previously been best known for correctly predicting the 2008 electoral outcomes of 49 states. So, in the weeks leading up to Obama v. Romney, when Silver's formulas predicted that the incumbent would take Nevada... Pennsylvania... Ohio... even Florida, liberals everywhere found it easier to sleep at night.
Now, as the Supreme Court considers the constitutionality of same-sex marriage, Silver has once again posted numbers that might sooth liberal folks' nerves. When it comes to shifting public opinion on gay marriage, Mr. FiveThirtyEight's forecast is wildly optimistic.
Silver used 2008 exit polling data from California, Florida, and Arizona-- which each had same-sex marriage ballot initiatives that year-- and "applied logistic regression to analyze how more than a dozen demographic characteristics affected these voters' decisions on same-sex marriage. In essence, the technique is to predict how likely an individual voter is to support same-sex marriage given their particular demographic profile."
From there, he stretched the demographic profile prediction across all 50 states and Washington D.C. That showed that in 2008 eight states plus D.C. had more than 50 percent support for same-sex marriage. He then extrapolated that model through 2020, adding the historical trend "that support for same-sex marriage will continue to increase by one-and-a-half percentage points nationally per year," a projected rate that varies based on a state's number of swing voters.
By 2020, according to that model, 44 states plus D.C. will support a pro same-sex marriage ballot initiative. Among them: Kansas (55.1), Texas (52.4), Kentucky (54.4), Oklahoma (51.2), and Utah (54.2). Nationally, 60.5 percent of Americans will support gay marriage.
Two-thirds of Californians will, too. But that would still put us closer to the center than 11 other states, including Rhode Island (75 percent) and Massachusetts (74.5).
For same-sex marriage supporters, these numbers might make SCOTUS' decision on Prop. 8 and the Defense of Marriage Act feel less ultimate. As long as public support keeps pace, gay rights legislation will inevitably follow.
But it's not necessarily that simple. Nate Cohn, at The New Republic, counters that Silver's gay marriage forecast likely overstates the trend-line for support in the South. He argues that the marriage equality push in in the Bible Belt will eventually run into a wall -- there are only so many open-minds to sway.
With evangelicals slower to change their minds, Southern states should move at a slower pace than the national average. To date, support for gay marriage has increased at a roughly linear rate of 2 points per year. But it's possible that increases in support could slow in the medium-term, as non-evangelical groups hit the point of diminishing returns. If evangelicals don't pick up the slack by shifting faster on gay marriage, support for gay marriage could plateau. Parts of the South, Plains, and West would probably still have gay marriage bans, and the Supreme Court, despite its hopes to avoid a judgment, might be forced to make the final call.
We'll have to wait nearly a decade to see if Silver's model pans out. In the meantime, the race between public opinion and legal policy pushes forward.