Mark Blumenthal | July 10, 2008
Topics: Party Weighing
I received an email reply from Scott Rasmussen to the questions I posted on Monday about their party identification numbers for June and about their procedures for weighting by party at the state level.
First, I had noticed a very slight difference (0.13%) in the Democratic party identification advantage they reported at the national level for June (9.37% vs 9.5%). Rasmussen confirms my hunch that filtering for "likely voters" narrows the advantage ever so slightly.
Second, he answered a far more important questions, how do they set targets for their party ID weights at the state level:
The question of states is more challenging and one we continue to work. Our initial targets are set by playing off the national numbers. We note changes from 2004 and/or 2006 and make comparable changes to the state targets from our polling in those years. Broadly speaking, if the number of Democrats are up 5 nationally compared to an earlier period, then the state numbers would be up five too. Due to demographic differences, not every state moves completely in synch with the national numbers, but they are close in our targeting formula.
Then, we monitor the state by state results as we conduct state polls and are in the process of making some modest mid-year adjustments now (in most states, we have at least 3,000 state specific political interviews to draw from, plus our national political tracking data, plus our baseline numbers from the other poll). Realistically, though, the current adjustments are very small. To this point, the national shifts appear to provide a good indicator. As we head to the fall, we will poll every competitive state at least weekly and do larger samples. This will enable our dynamic weighting process to draw upon up to 10,000 state-specific interviews or more to set the targets for key states.