As you may have noticed, we have inserted a new map at the top of our main page. The classic maps for President, Senate, Governor and House races are still there, just use the "map chooser" pull-down menu to see them. We will be live blogging tonight, starting a little after 5:00 Eastern Time.
Here is a quick description of the numbers in the map and where we get them.
First, we will be monitoring the five major television networks and the Associated Press and tracking the calls that each makes in the race for President. Once one network projects a state for a candidate, we will color the state light red or light blue for McCain or Obama. When all six organizations have made their projections, we will change the map to a darker shade of red or blue. States where the polls have closed, but where it is still too early or too close to call, will be colored yellow (also the color we will use in the extraordinarily unlikely event that any of the networks make a conflicting call).
To see which networks have made their projections, just point your cursor at the state to see an expanded "tool-tip" displaying that information. The tool-tip for each state will also display two important columns of data:
Pollster Trend -- The far right column will display our most recent trend estimate based on the pre-election polls. And just like our standard map, you can click on the state to display our chart for that state. See our map FAQ for more information on how we compute our trend estimates.
Est Result -- Shortly after the polls close, we hope to display the "estimated result" of the vote shares in each state culled from the network exit poll tabulations posted online (by CBS, CNN, Fox and NBC). These tabulations show the exit poll results by demographic and other subgroups (age, race, party, etc.). We will extrapolate the underlying vote estimates used to weight each table and display these in the Estimated Result column on the tool-tip.
During the course of election day and evening, the people who run the exit poll and projection operation have various estimates of the outcome in each state, estimates that gradually improve as they obtain first exit poll interviews, later the actual vote cast in random samples of precincts, and ultimately the actual vote count. When the polls close, and at two or more additional times during the night, the analysts will re-weight the tabulations based on more current and accurate estimates.
Important disclaimer: These estimates are most likely not undiluted "exit poll" results. At poll closing, the exit poll tabulations that appear online are most likely weighted to a "composite estimate" that averages the results of exit poll interviews with the averages of pre-election polls (not at all unlike the trend estimates we post here at Pollster.com). Also, as we learned during the primaries, the weighting of the cross-tabulations frequently falls far behind the up-to-the-minute estimates that network "decision desk" analysts use to call the race.
Note that we have added separate labels for the individual congressional districts of Nebraska and Maine, since these states allocate Electoral Votes partially by district and may split their electoral votes. Unfortunately, we were only able to obtain public polls for Nebraska-02, so that label is the only one of the districts that will click-thru to a chart.
Follow Mark Blumenthal on Twitter: www.twitter.com/MysteryPollster