Saturday, September 27, 2008

Interactive charts now at

If you can't resist the urge to play with the data, we have new charts at that can satisfy your need. These are interactive versions of the charts here and previously at Pollster. You can exclude pollsters or methods. You can change the sensitivity of the fit to either more sensitive or less sensitive than our standard fits here.

Here is a sample chart for Ohio, using our default values:

And here it is again but mail and Internet polls excluded and more sensitivity:

Give it a try and let us know if you run into any problems. You can embed the results of your experiments on your own page, though not the interactive features.

At the moment the embedded graphs are scaled at 450 pixels wide. To fit them here I edited the html code to make the width 400 and the height 308. I hope we can automate that soon, but meanwhile if your width is fixed and below 450, changing two lines in the embedded html will fix it for you.

These charts are available for a growing number of states at Stop by and play!


Monday, September 22, 2008

Obama Recovery Across Red, Yellow and Blue States

Obama has now recovered his lead in national polling, rising at or above his post-DNC, pre-RNC level. This sharp turnaround erases the very sharp pro-McCain/Palin convention bounce we saw in early September.

But the Obama recovery is not concentrated in Democratic states. As with the McCain advantage, this turn is visible in all three types of states-- Red, Yellow and Blue.

The biggest recovery is actually in the Red states, where McCain enjoyed his biggest bounce. Those states are not back where they started, or even a shade less pro-McCain, but they are a far ways from being "close".

The states we have classified as tossup or leans (what I'm calling yellow here, though on the map leans are light red or blue) have also seen a significant Obama recovery. The range of movement is rather modest, but the roughly three point McCain gain has now been balanced by a 3+ point Obama recovery in these most contested states, putting Obama up by just over a point.

Dem states showed a small move to McCain and have now seen an Obama recovery, though with a one point fall off most recently.

Monday, September 15, 2008

McCain Gains Not Limited to Red States

Obama advisor David Axelrod is quoted in today's Washington Post article by Dan Balz and Peter Slevin:

"I think one of the things driving the national polls is that the red states are redder," said David Axelrod, one of Obama's closest advisers. "In the battleground states, the race has held pretty firm."

An interesting claim. Let's take a look at the data based on state polls, rather than national.

Among the strong Republican states, McCain has gained more than 8 points over Obama since shortly before the conventions, turning a 14 point lead into a 22.5 point margin, a huge gain.

Among the strong Democratic states, the effect of the conventions is a tiny 2 point move in McCain's direction, from an Obama lead of 12 points before to 10 points now.

But the rest of the states, rated lean or toss up, have also shown movement. These swing states had a 1.5 point Obama lead before the conventions, and that has now turned into a 3 point McCain lead, a 4.5 point shift.

So Axelrod is right that the biggest gains for McCain have come in the reddest of states, and those may influence national polling. But the evidence doesn't back his second claim, that the battleground has held firm, unless of course you mean they are still battleground states. But now battlegrounds that on balance favor McCain rather than favor Obama as they did before the conventions.

One caution: the lean and tossup states are themselves heterogeneous, so a single trend estimate such as the 4.5 McCain lead here is itself a simplification. If you wanted to focus on the six or eight states that probably hold the key to the electoral vote, you could slice this more finely.

We currently rate eight states as pure tossup: NH, VA, OH, MI, CO, NM, NV and MT. (Note the last has few polls and the latest 9/8 shows a 53-42 McCain lead. But it does fit our statistical criteria, and Montana was listed by the Obama campaign as a target state.)

When we fit the data to just these eight tossup states, we see a 3.5 point move in McCain's direction, from a 2 point Obama lead to a 1.5 point McCain lead. Only a point less shift than among all lean and tossup states.

No matter how you slice it, the battleground states have a lot of battle left in them, and campaign events are having effects across all states, though larger in some than others.

Friday, September 12, 2008

Alaska Post-Palin

Alaska has long been a solidly "red" state but this year the troubles of the state's Senator Ted Stevens and Representative Don Young on top of Republican party "brand" troubles suggested there might be an opportunity for the Obama campaign which spent $88,000 in advertising in the state in June and July according to the Wisconsin Advertising Project.

And then came Sarah Palin to the Republican ticket. The impact is obvious in the chart above.

While the state was classified as "lean Republican" prior to the Palin Pick, all but one poll in the state showed McCain ahead. Now there is no doubt.

The politics are obvious, of course, but it is a nice example of how a political event can be instantly reflected in the polling, and bring our trend estimator to a sharply different conclusion.

State and National Polling Post-Convention

The gains of the Republican ticket continue in both state and national polling as more post-convention state polls become available. We now have 26 states with a post-convention poll and the results mirror the sharply pro-Republican movement seen in national polling since Sen. McCain's acceptance speech.

The McCain lead is now about 3 points in national polling and is just under 4 points for those states with post-convention polls.

An important point is that the states with post-convention polls are not a representative sample of all states, though the differences between states without a recent poll and those with new polls is not large. States without new polling have averaged 2.1 percentage points more pro-Obama than those states with new polling. However, if we plot the trend lines in the chart for all states (with or without new polls) and for those with post-convention polls, we see the two trends have followed similar if not identical trajectories.

Since our last update of this comparison of state and national trends the addition of new states has brought the state trend line a bit below the national polls trend, something not so visible in the earlier post. This difference reflects the selection of states that have new polling, rather than shifts in the vote margin in the states, except of course for the brand new polls.

The bottom line is that the swing towards the Republicans remains strong in both state and national polls , amounting to a 7 point national swing and a 5 point swing based on the state polls. In an earlier post, I pointed out
The bottom line is neither campaign should be complacent or despondent. There is a lot of time left and recent history shows that both up and down swings of 6-9 points are entirely plausible.
Right now that magnitude of swing is looking about right.

The states with post-convention polls are: Alabama, Alaska, Colorado, Florida, Georgia, Idaho, Maine, Maryland, Michigan, Mississippi, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, North Carolina,North Dakota, Ohio, Oklahoma, Pennsylvania, Virginia, Washington, West Virginia, Wisconsin, Wyoming.

Wednesday, September 10, 2008

Ins and Outs of Polling

I did an hour on Minnesota Public Radio on September 10 discussing polling techniques and issues. Here is a link to the audio. Good callers!

The focus on polling starts at 11:00 minutes into the show.

Post Convention Bounce in the States

The McCain campaign has gained significant support in national polling since the end of the Republican Convention, but what about the state polls? Has the shift also been reflected there?

State pollsters appeared to go on vacation for the conventions, with very little new polls during the two weeks of conventions (and the week before). Now the pollsters are back, tanned and rested and ready to go. We've added 17 new state polls since the RNC ended, and while we'd love to see more, it is enough to get started with some analysis.

The chart above shows the national trend in blue and the trend based on those states with post-convention polls in purple. Over the course of the year, the two trends have followed each other rather well with some small differences in details but qualitatively similar patterns of up and down movement.

Now in the post-RNC period, the states with new polls match the national polls quite closely, both giving estimates of about a one point McCain lead, with the states maybe a shade less than that.

This post-convention bounce may or may not last, but at the moment the evidence is that it is moving across the states (and these are mostly competitive states) at about the same rate as it is for the national polls.

The state polls show no positive DNC upward bounce, but that's because there were practically no new polls during that period, so don't jump to that conclusion. It is an artifact of no polls.

States for which we have new polls are Colorado, Florida, Maryland, Michigan, Montana, New Jersey, North Carolina, Ohio, Oklahoma, Pennsylvania, Virginia, Washington and Wisconsin.

Monday, September 08, 2008

Republican Bounce and Trend Sensitivity

The post-convention bounce is now moving in the Republican direction, but with an enormous spread in estimates. A Gallup/USA Today (9/5-7) has an enormous 10 point McCain lead over Obama, 54%-44%. In contrast, Gallup's tracker over the same days shows a 5 point McCain lead, 49%-44%. Now would be a good time to note that the tracker is a registered voter (RV) sample, while the Gallup/USAT is a likely voter (LV) sample. LV samples typically are more favorable for Republican candidates, so at least some of this difference is probably due to these different sampling frames. We'll no doubt be talking a lot about this issue in days ahead.

But other polls on the same days show a tied race. Diageo/Hotline has the race 44%-44% and CNN has it 48%-48%. And Zogby's Internet poll done 9/5-6 puts the race at 50%-46%.

All of these are much better for McCain than the 5-9 point Obama leads we saw in the immediate aftermath of the Democratic convention.

So it looks like both parties got nice convention bounces.

Our trend estimate is still hungry for more data. The standard, blue line, estimate is now less persuaded that Obama had a convention bounce OR that McCain is getting one either. That is standard behavior of our estimator which is designed to be a bit conservative when faced with conflicting polls and short term changes of trend.

But that is why we have our "sensitive" estimator for comparison. The red line is a trend estimate that is about twice as sensitive a the blue line. It is considerably quicker to respond to short term changes and to fewer polls. The down side is it will often chase random noise.

Since there is good reason to believe convention bounces are real, it is reasonable to think that the red line's indication that the race has indeed tightened is probably a real signal in the data, and not just noise. On the other hand, the Gallup 10 point McCain lead is out of the range of any other current polling data. So "red" may be chasing that outlier just a bit more than is good for him. As the figure makes clear, red and blue usually agree quite closely after enough data are in hand, but can diverge especially when data are sparce.

A prudent approach is to wait for a few more post-convention and post-weekend interviewing polls to see just how big and how sustained the RNC bounce is. But both estimators agree we have ourselves a real horserace now.