Today's flood of new national surveys provides enough raw material for a week's worth of blog posts. The new surveys are from ABC News/Washington Post, CBS/NY Times, CNN/ORC and USAToday/Gallup, plus one more from Newsweek released over the weekend. I want to highlight a few key results, particularly what the new surveys tell us about shifts in the so called "generic congressional" ballot.
As Charles Franklin notes in the previous post, these surveys do indicate an improvement in the Democratic margins. I want to take a closer look at an issue that inevitably confronts us when considering the generic ballot question, whether to watch results among all registered voters or just the sub-samples of "likely voters" as defined by each pollster. The surveys from CNN, Gallup and Newsweek provide both, so the following table provides both.
While some of the surveys (Gallup and CNN) show more change than others, all but CBS/NYTimes poll showed at least some improvement in the Democratic margin since September. When we average the results of the registered voter samples, the Democratic margin increases from 11 to 14 percentage points.
When we shift to likely voters, things get a little murky. Only two of the newest polls -- the ones from Gallup and CNN -- reported results for likely voters in both September and October. And both show bigger swings toward the Democrats, but among both their likely and registered voter subgroups. The change for Gallup among likely voters is simply enormous (from a dead heat to a 23 point Democratic advantage). CNN also shows an eight point gain in the Democratic margin among likely voters (from 13 to 21 points).
So which population should we follow? Frank Newport made the case for the Gallup likely voter model in a post here last week, and a lively debate ensued that will no doubt continue over these new results. Consider the following table that shows how likely and registered voter results have compared since Labor Day on the pollst that reported both.
There is no apparent consistency in the differences between the registered and likely voter samples. On average they seem to make the margin about a point less Republican, but even that disappears when we remove the mid-September USAToday/Gallup poll from the analysis. Consistent with past criticism, the likely voter model appears to be producing more volatile results, particularly for Gallup. But for all the sound and fury of the debate, likely voters and registed voters are looking more or less the same.