While most liberals were out celebrating the news that both Iowa and Vermont legalized same-sex marriages, political statitician extraordinaire Nate Silver did what he does best: the math.

Nate Silver is a University of Chicago economics student turned statistics renaissance man. Baseball fans know him for inventing the PECOTA forecasting system, and political junkies know him from his deadly accurate election predictions at FiveThirtyEight.com. With the election in the past and the PECOTA invention helping pay the bills, Silver has had plenty of time to tell the story of the political world through the wonderful world of math. A recent issues he tackled was the divisive gay marriage maelstorm.

One of the big stories of the recent weeks are the decisions in Iowa and Vermont supporting gay marriage. The rulings by the Iowa supreme court and the Vermont legislature came as a shock to many, with opponents of gay marriage enjoying heady times in recent years. President Bush was aided in his 2004 re-election bid by gay marriage ban referendums in eleven states; California recently passed Proposition 8, which made gay marriage unconstitutional; and our own state passed a gay marriage ban in 2006.

Despite gay marriage bans on the books in 29 states, recent polling has shown a trend more support for an expansion of the institution. (link: http://www.fivethirtyeight.com/2009/04/gay-marriage-by-numbers.html) Based on the polling data, support for gay marriage has gained about eight percentage points since 2003, and currently, the pro-ban position has been losing an average of two percentage points per year nationwide.

Motivated by the news from Iowa and Vermont, Silver decided to see if there is a way of using the liberalizing social trends to predict the future fate of gay marriage ban referendums in the United States. (link: http://www.fivethirtyeight.com/2009/04/will-iowans-uphold-gay-marriage.html)

He explains the method as follows:

I looked at the 30 instances in which a state has attempted to pass a constitutional ban on gay marriage by voter initiative. The list includes Arizona twice, which voted on different versions of such an amendment in 2006 and 2008, and excludes Hawaii, which voted to permit the legislature to ban gay marriage but did not actually alter the state's constitution. I then built a regression model that looked at a series of political and demographic variables in each of these states and attempted to predict the percentage of the vote that the marriage ban would receive. It turns out that you can build a very effective model by including just three variables: 1. The year in which the amendment was voted upon; 2. The percentage of adults in 2008 Gallup tracking surveys who said that religion was an important part of their daily lives; 3. The percentage of white evangelicals in the state.

Silver’s analysis clearly shows that of the three identifiable factors, two are based on religion. It is not my intent for this post to devolve into an anti-religious screed, so the primacy of religion in influencing discrimination against gays is noted solely as an interesting, but not shocking, result of the study.

Looking at the results from a results-based standpoint is much more instructive for the current state of gay marriage in our state. Not surprisingly, his model predicts that states such as Vermont, Massachusetts and New York would vote against a gay marriage ban today, and that it is going to take until almost 2025 for support for gay marriage bans to drop below 50% in Alabama and Mississippi. Closer to home, the model predicts that the citizens of Wisconsin would vote against a gay marriage ban three years from now in 2012.

The issue of gay marriage in Wisconsin was not put to rest when the gay marriage ban passed in 2006 with the support of 59% of voters. The Badger Herald reported on Friday that the state’s Supreme Court will be assessing the constitutional validity of how the gay marriage ban amendment was presented to voters in 2006. If the gay marriage ban is ruled unconstitutional under the current suit, Silver’s regression model suggests that the window available for anti-gay activists to get the gay marriage ban on the ballot and passed a second time is quite narrow. It also means that if they want the ban to stay on the books in Wisconsin, they must do everything they can to make sure the Supreme Court upholds the ban.

For gay rights activists, the data presented on FiveThiryEight.com suggests that the tide of discrimination against gay marriage is turning in their favor. Even if the marriage ban is upheld by the state Supreme Court, the polling shows that the citizens of Wisconsin are becoming more accepting of gay marriage, and soon a majority of them should be opposed to a gay marriage ban. If the current trends hold and the gay rights groups organize effectively, favorable conditions for overturning the 2006 referendum should be present in the state in the near future.