Rasmussen constantly adjusts their party ID numbers so their daily tracking polls portray an accurate view of the electorate as a whole…
The targets are not set arbitrarily. Rather, they are established based upon survey interviews with a separate sample of adults nationwide completed during the preceding six weeks. A total of 500 nightly interviews are conducted for a total of 21,000 interviews over the six week period.
And here’s how much variance they’ve seen in party ID in September…
For polling data released during the week of September 21-27, 2008, the partisan weighting targets used by Rasmussen Reports will be 39.0% Democratic, 33.5% Republican, and 27.5% unaffiliated.
For the preceding week, September 14-20, 2008, the targets were 38.7% Democratic, 33.6% Republican, and 27.7% unaffiliated.
For the first thirteen days of September, the targets were 39.7% Democrat, 32.1% Republican, and 28.2% unaffiliated.
Just a little look behind the curtain so you know the “how” of these daily tracking polls.