Saturday, January 16, 2010


The Winning Scott Brown Party ID Coalition Seen in the Suffolk Poll

Politics is one of the best examples of the phrase "history repeats itself". As I illustrated last night, Public Policy Polling is betting on this phrase with concern to its turnout model for the Massachusetts Special Senatorial Election. But history is not just limited to turnout, people's voting habits are also relatively consistent. That is, the people inclined to vote for a Democratic candidate in one election are much more likely to vote for a Democratic candidate the next election than a person who voted for a Republican candidate. At the same time, swing voters (those who could vote for either party's candidate) tend to be consistently swing voters. With this idea in mind, we should expect that in order for Republican Scott Brown to win in Massachusetts, he will need to put to together a similar coalition as those past Republicans who won statewide.

Unfortunately for our analysis and Republicans, Massachusetts' Republicans rarely win statewide races and have not won a Senate election since 1972 (making a Brown win all the more unbelievable). The last time a Republican won a statewide election in Massachusetts and an exit poll is available was 1998. In that year, Republican Paul Cellucci defeated Democrat Scott Harshbarger 50.8% to 47.4%, nearly identical to the 50%-46% Republican Scott Brown holds in the latest Suffolk University poll. The question we should be asking is "does this make sense?" Do the internals (what percentage of the electorate certain groups of voters make up and how these groups of voters are voting) match up with what we would expect Brown would need to win in 2010?

The first statistic we need to look is whether Suffolk seems to be projecting what I outlined as the most likely turnout model. Note that Suffolk's poll asks party identification in a different way than exit polls, but I have previously pointed out that this should not affect the polls results. Suffolk's poll expects 39% of the electorate will be registered Democrats, 44% undeclared (roughly independent), and 15% Republican. This breakdown is almost identical to the turnout seen in 1998. I personally expect the turnout will be slightly more Democratic and Republican and slightly less Independent.

What about the vote among among these demographics? In 1998, Cellucci won the election with 23% of the Democratic vote, 61% of the Independent vote, and 85% of the Republican vote. What about Scott Brown? Brown's locked up 17% of the Democratic vote, 65% of the Independent vote, and 91% of the Republican vote. These coalitions are very close. The reasons for these slight differences can easily be explained by a number of factors including margin of error, which is anywhere from 6.5% for the independent subgroup to 11.3% for the Republican subgroup in the Suffolk poll. Another contributing factor is that the 2010 electorate is simply more polarized because Democrats love Obama and Republicans hate him, and this vote is largely seen as a referendum on a Democratic Presidential administration.

Finally I wondered what happens if we apply my expected turnout among Democrats, Independents, and Republicans to the expected votes among these groups in the Suffolk poll? Brown's lead drops, but he still is favored 49%-47%.

As I said last night, Brown should be considered the favorite.

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