Monday, August 28, 2006

Generic Ballot: New polls mostly below trend

Recent Generic Ballot polling has fallen a below the trend estimate. In polls taken since the British terror plot against airlines, five of the seven polls have shown a reduced Democratic advantage. The largest change is the Gallup poll, which on other grounds appears to be an outlier. However, other less extreme results also show some rise in Republican support. The effect of this is not to turn the trend estimate down, but to flatten it at +12 for the Democrats.

Estimates that are more sensitive to the latest polls show a slight downturn in the trend, but those are also subject to being heavily influenced by the Gallup outlier. For that reason I favor the more conservative estimate.

Interestingly, the post-plot polling does not show any evidence for an upturn in overall presidential approval. It would seem a little odd if the plan plot affected the congressional ballot but not presidential evaluations. So for the moment I think the trend estimator reading "steady" rather than changing is supported by the evidence.

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