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Stochastic Democracy aggregates polls, makes graphs, and does some regressions to get an idea about the Democrat's chances in 2012.

*Cross-posted at StochasticDemocracy.com*

With renewed media focus on House Generic Ballot polling, it's a good idea to see how things have shifted since the election:


The past two months of Generic Ballot Polling. For a full table, click here.


In a familiar pattern, Rasmussen polling strongly diverges from everyone else. And the relative frequency of Rasmussen vs non-Rasmussen polling at any given point swamps any actual change of opinion any naive poll filtering method.


Large Statistically significant house-effects

In order to get an idea about how many seats the Democratic party can expect to win from a generic ballot result, we do a simple univariate regression relating overall Democratic vote with the percentage of seats won by Democrats in presidential elections since 1948. This is somewhat crude, but because we don't know what the districts will look like in 2012, more sophisticated analysis isn't really possible.


In order to tease out differences in pollster differences and the LV-RV disparity, we've used our 2010 poll filter that adjusts for house-effects.


House-effect adjusted estimates of Democratic Vote-Share over time in the Generic Ballot among Registered Voters with one standard deviation confidence intervals shown.

That's a registered voter estimate. Republicans almost always perform better among likely voters than registered voters, and the extent of this difference is often called the "Enthusiasm Gap".


Discrepency between Likely and Registered polls in the last four national elections, estimated using Stochastic Democracy's Bayesian DLM model with House-Effects in a previous post.

Using this, we can construct estimates conditional on different turnout scenarios:

This is all consistent with a very close race for control of the House of Representatives in 2012. While this analysis shows a very slight edge for the Democrats, they face a disadvantage due to large Republican gains in state legislatures that will effect voting law and redistricting, and due to incumbency advantage working in the Republican's favor due to their strong performance in 2010. Intrade puts the Democrat's chances at 42%, which seems reasonable.

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