Wednesday, October 29, 2008

Undecided Voters and Racial Attitudes

How will undecided voters break, and will racial attitudes color their votes?

We've seen an enormous amount of speculation but little evidence based on data, so let's try to tip the balance back to empirical evidence.

Thanks to the Diageo/Hotline tracking poll data, we can model individual vote choice and see what we would expect of undecided voters.

During October 3-11 our colleagues at the Diageo/Hotline poll included a racial attitude question we had previously used in the Big Ten Battleground survey in September and which NBC/Wall Street Journal used in January. That question was shown in both the earlier polls to have a statistically significant effect on vote choice, even after controlling for other political attitudes and demographics.

The question text is: "I'd like you to tell me whether you strongly agree, somewhat agree, somewhat disagree or strongly disagree with the following statement. ... African Americans often use race as an excuse to justify wrongdoing"

58% of the total sample, and 61% of whites agree either strongly or somewhat. (For comparison, 56% of hispanics and 40% of African Americans agree strongly or somewhat.)

I model the vote choice for those who expressed a preference with a model using a variety of attitudes and demographics, including favorability to Obama and McCain, party id, marital status, kids at home, education, race, age, sex, church attendance, region and urban, suburban or rural residence. Then I added the racial attitude responses from the "black excuse" question. To check against people hiding their feelings by refusing to answer the "black excuse" question I also included a variable to capture the effect of refusal to answer.

This model produces a predicted probability of voting for McCain or Obama, including predicted probabilities for those who had said they were undecided or who refused to respond to the vote question. From this we can estimate the likely vote of undecided, and compare the estimates to the responses of those who gave a vote preference in the survey.

Bottom line: Undecided and refuse to say voters are estimated to break 50% for McCain and 50% for Obama. As even as it gets. There is no evidence here of a large bias towards McCain that is hidden within the undecided respondents.

Nor is there evidence of a pronounced racial bias among these undecided voters as compared to the public at large. Among the undecided 27% strongly agree and 32% somewhat agree on the "black excuse" item. For the public as a whole 26% and 32% give the corresponding responses.

The model does a good job predicting survey response as well. 97% of both Democratic and Republican voters are predicted by the model to vote that way. For those who say they only "lean" towards one party or the other, 77% of Democratic leaners and 80% of Republican leaners are predicted to vote as they lean. The symmetry of results here suggests that there is not a visible bias in the model estimates for either party or for intensity of preference.

Finally, what happens if we ignore racial attitude and predict vote among the undecided without it? The split is 52% Obama to 48% McCain. So at most the impact of incorporating racial attitude in the model is a rise of 2% for McCain among undecided. Given the sample sizes involved, that is well within the margin of error. And if we take out candidate favorability from the model we get estimates of 52-48 without racial attitude and 53-47 with racial attitude.

So what can we conclude? There is no evidence of a hidden support for McCain among undecided voters. They split more evenly than does the "decided" pool of respondents, who split 54-46 in this sample (Oct 3-11) but that's well within normal expectations and is a modest difference in any case.

Second, the role of racial attitude is important at the individual level, but the aggregate consequence is extremely modest. Some are moved away from Obama yet others are moved towards him. And among the undecided, the distribution of opinion on this measure of racial attitude is virtually identical to that in the population.

In a year of endless discussion about racial effects there has been far more speculation and far less data analysis than is good for us. Let's put our data on the table before continuing to opine about this subject.

Cross Posted at

Friday, October 17, 2008

The Road to 270 for McCain

(Click chart to see full size)

It takes 270 to win this game. McCain is behind in national polls, down 7.5 in our Trend Estimate. But as you know, this is a game won in the states. So what does it now take for McCain to eek out a 270-268 electoral vote win?

The chart above shows the states allocated to candidates based on my Political Arithmetik trend estimate. The classification of states is the same as Pollsters, but differ slightly in the order.

The states are ordered left to right according to the Obama minus McCain margin. Yellow states are classed as tossups but are allocated to candidates based on who is ahead in the trend, no matter how small that margin may be. The width of each state's block is proportional to the state's electoral vote.

With this classification, Obama has 364 electoral votes to McCain's 174.

So what would it take for McCain to come back at this point? Ohio and Florida, above all else.

Ohio and Florida are the largest states that are in Obama's row but still close. McCain led in both states in August and the first half of September. Without them, it is hopeless. With them, he still needs more, but they are the necessary conditions for a win.

Can he do it? The trends in Ohio and Florida offer a small glimmer of hope. While most states have continued to move in Obama's direction (see PA, MI and WI), these two have leveled off, and in Ohio moved back in McCain's direction.

No matter what, McCain has a long shot to get to 270. But The road has to go through Ohio and Florida and both states are looking better for him than any others he must win. What he is doing in Pennsylvania and Wisconsin is a mystery to me.

Sunday, October 12, 2008

Tracking Poll House Effects

There are six daily tracking polls currently reporting data, up from just two (Gallup and Rasmussen) during most of the year. How are they doing?

Compared to our trend estimate based on all public polls, not too bad. The trend based on trackers only is close to that for the all polls trend, with an average difference of just 0.35 percentage points, a very slight under-estimate of the Obama minus McCain margin. Recently the difference has been negligible, with most of this difference coming early in the year.

A bit of visual inspection shows the GW Battleground poll seemed more out of line until they shifted their party weighting plan after a few days. Likewise Hotline had a couple day "hiccup" but has returned to trend.

What about house effects? The range is moderate, from +4.3 points on the margin for Daily Kos, to -4.2 points for Zogby, though the latter has only just started polling so the confidence interval is wide.

Monday, October 06, 2008

National Sensitivity Comparison

Now that you can play with the sensitivity of the trend estimate on our interactive charts at, the need for my sensitivity comparisons is somewhat less. But, it is interesting to see that just now the sensitivity used in our national trends makes very little practical difference.

My pals, "Ready-Red" and "Old-Blue" are in good agreement on both the magnitude of the Obama surge in the last three weeks, and the current standing of about a 7 to 7.5 point Obama lead.

Red had a moment of indecision last week when a couple of polls showed McCain ahead, but after barking in that direction, Red came back to Old Blue in seeing continued upward movement for Obama. You gotta love Red for his sensitive nose, but sometimes it distracts him from the big picture.

So here is a question to ponder. How much more upward lift can there be for Obama? He's already well beyond his previous best. Does anyone believe he really can hold a 10 point lead through the election? If not, then we should see some flattening out in the next few days, regardless of the debates.

Campaign '08 vs '04 and '00 Update

The 2008 campaign had not seen a really big move in preferences until the financial crisis hit three weeks ago today. Since that time, the Obama-McCain margin has shifted almost 9 points in Obama's favor, converting a small McCain lead into a substantial Obama advantage.

This swing reversed the gains McCain made with the Republican convention and the week after during which he picked up about 4 points and took the lead for the first time since March.

I wrote earlier that we had not seen a move in 2008 as large as ones we saw in both 2000 and 2004. That is no longer true of 2004, though the current run is not yet as large as the one Gore mounted in 2000.

The Bush counter-assault in 2000, after Gore's surge, was almost eight points, and began at almost the same point in the campaign, about 57 days out.

Voters are making up their minds at about the same rate as they did in 2000. If this year follows that pattern, look for some serious decision making over the next two weeks.

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.

Friday, August 29, 2008

State Battlegrounds and Home Grounds

A quickie from Detroit Metro Airport.

Mark Blumenthal reported on an interview with Obama campaign manager David Plouffe yesterday at Pollster. Plouffe discussed the 18 states the Obama campaign sees as their target states, and Mark reported what states those were in his post.

Here we take a quick look at the polling in those states. The chart above is sorted by the Obama minus McCain margin, and shows the 95% confidence interval. The dot size is proportional to electoral vote.

Below I show the status of the states based on our polling categorization of each state.

Time to run for the plane.

Wednesday, August 27, 2008

McCain, Obama and Clinton Favorability

A little interesting movement in views of the candidates has taken place since the end of the primaries in June. All three candidates, McCain, Obama and Clinton, have seen rises in their favorable ratings and an initial decline in unfavorable views though with a slight upturn recently. McCain and Obama are enjoying essentially identical ratings, with 60% favorable and only 35% unfavorable. Even after a significant amount of negative portrayals of him in RNC and McCain ads, Obama's rating has risen over the summer, and so has McCain's. (According to the Wisconsin Advertising Project, which monitored and coded all 100,000 ad airings in June and July, one third of McCain's ads contained negative information about Obama and 100% of RNC ads were negative. In the same two months, 10% of Obama's ads mentioned McCain.)

Whatever happens after the conventions, both candidates enjoy an enviable standing with voters as attractive figures instead of a pair of lesser evils. The fall capaign may alter this, but even after a hard fought primary season the nominees remain attractive figures.

Meanwhile, Senator Clinton has also enjoyed an upturn in favorable ratings and a decline in unfavorable ratings since the end of the primary season. While improved, Clinton remains a more polarizing figure than either McCain or Obama, with slightly lower favorable but noticeably higher negative ratings.

Senator Clinton is far more popular among Democrats than among either Independents or (especially) Republicans. In that sense, her speech to the Democratic Convention last night was an example of speaking primarily to the party and her supporters, rather than to the broader public. The contast between former Virginia governor and now Senate candidate Mark Warner's speech and Clinton's is a good example of this difference. Warner stressed unifying themes and appeals across political groups, which was greated warmly but which fell short of electrifying the Democratic delegates. In contrast, Clinton played to the party and produced a predictably enthusiastic response within the DNC convention hall. Conventions contain both elements. Monday, the party celebrated Sen. Kennedy's life and family legacy, primarily an inside the family affair, perhaps touching some independents but not likely to attract Republicans. In contrast Michelle Obama's speech could have easily been given at the Republican convention, with its themes of family, hard work, pulling oneself up from working class circumstances. Hers was a speech designed to reach out beyond the party.

The one remaining question from the Clinton speech is whether her supporters also resepect her enough to follow her lead. For Clinton to be a power in the party includes the requirement that she be able to deliver her supporters for Obama. If any significant number of her supporters refuse to be delivered, they reduce her status as a result. This is hard to judge from the cable news coverage, who can easily find individual delegates willing to say they are unpersuaded. But what effect the Clinton speech has with her supporters outside the convention hall will be critical.

Sunday, August 24, 2008

How Pollsters Affect Poll Results

Who does the poll affects the results. Some. These are called "house effects" because they are systematic effects due to survey "house" or polling organization. It is perhaps easy to think of these effects as "bias" but that is misleading. The differences are due to a variety of factors that represent reasonable differences in practice from one organization to another.

For example, how you phrase a question can affect the results, and an organization usually asks the question the same way in all their surveys. This creates a house effect. Another source is how the organization treats "don't know" or "undecided" responses. Some push hard for a position even if the respondent is reluctant to give one. Other pollsters take "undecided" at face value and don't push. The latter get higher rates of undecided, but more important they get lower levels of support for both candidates as a result of not pushing for how respondents lean. And organizations differ in whether they typically interview adults, registered voters or likely voters. The differences across those three groups produce differences in results. Which is right? It depends on what you are trying to estimate-- opinion of the population, of people who can easily vote if the choose to do so or of the probable electorate. Not to mention the vagaries of identifying who is really likely to vote. Finally, survey mode may matter. Is the survey conducted by random digit dialing (RDD) with live interviewers, by RDD with recorded interviews ("interactive voice response" or IVR), or by internet using panels of volunteers who are statistically adjusted in some way to make inferences about the population.

Given all these and many other possible sources of house effects, it is perhaps surprising the net effects are as small as they are. They are often statistically significant, but rarely are they notably large.

The chart above shows the house effect for each polling organization that has conducted at least five national polls on the Obama-McCain match-up since 2007. The dots are the estimated house effects and the blue lines extend out to a 95% confidence interval around the effects.

The largest pro-Obama house effect is that of Harris Interactive, at just over 4 points. The poll most favorable to McCain is Rasmussen's Tracking poll at just less than -3 points. Everyone else falls between these extremes.

Now let's put this in context. We are looking at effects on the difference between the candidates, so that +4 from Harris is equivalent to two points high on Obama and two points low on McCain. Taking half the estimated effect above gives the average effect per candidate. The average effects are at most 2 points per candidate. Not trivial, but not huge.

Estimating the house effect is not hard. But knowing where "zero" should be is very hard. A house effect of zero is saying the pollster perfectly matches some standard. The ideal standard, of course, is the actual election outcome. But we don't know that now, only after the fact in November. So the standard used here is the house effect relative to our Pollster Trend Estimate. If a pollster consistently runs 2 points above our trend, their house effect would be +2.

The house effects are calculated so that the average house effect is zero. This doesn't depend on how many polls a pollster conducts. And it doesn't mean the pollster closest to zero is the "best". It just means their results track our trend estimate on average. That can also happen if a pollster gyrates considerably above and below our trend, but balances out. A nicer result is a poll that closely follows the trend. But either pattern could produce a house effect near zero. For example, Democracy Corps and Zogby have very similar house effects near -1. But look at their plots below and you see that Democracy Corps has followed our trend quite closely, though about a point below the trend. Zogby has also been on average a point below trend, but his polls have shown large variation around the trend, with some polls as near-outliers above while others are near outliers below the trend. The net effect is the same as for Democracy Corps, but the variability of Zogby's results is much higher.

Incidentally, the Democracy Corps poll is conducted by the Democratic firm of Greenberg Quinlan Rosner Reserch in collaboration with Democratic strategist James Carville. Yet the poll has a negative house effect of -1. Does this mean the Democracy Corps poll is biased against Obama? No. It means they use a likey voter sample, which typically produces modestly more pro-Republican responses than do registered voter or adult samples. Assuming that the house effect necessarily reflects a partisan bias is a major mistake.

How can you use these house effects? Take a pollster's latest results and subtract the house effect from their reported Obama minus McCain difference. That puts their results in the same terms as all others, centered on the Trend Estimate. This is especially useful if you are comparing results from two pollsters with different house effects. Removing those house differences makes their results more comparable.

What impact do house effects have on our Trend Estimate? A little. Our estimator is designed to resist big effects of any single pollster, but it isn't infallible, especially when some pollsters do far more polls than others or when one pollster dominates during some small period of time. We can estimate house effects, adjust for these, and reestimate our trend with house effects removed. The result runs through the center of the polls, but doesn't allow the number of polls done by an organization to be as influential.

The results are shown in the chart below. The blue line is our standard estimator and the red line is the estimate with house effects removed. Without house effects the current trend stands at +2.0 while ignoring house effects produces an estimate of +1.7. A little different, but given the range of variability across polls and the uncertainty as to where the race "really" stands, this is not a big effect.

The impact of house effects isn't always this small. Looking back along the trend we see that the red and blue lines diverged by as much as 1 point in late June, an effect due significantly to the large number of Rasmussen and Gallup tracking polls during that time and few polls with positive house effects in that period. A smaller but still notable divergence occurred in late February and early March.

The bottom line is that there are real and measurable differences between polling organizations, but the magnitude of these effects is considerably less than some commentary would suggest. Many of the house effect estimates above are not statistically different from zero. Even ignoring that, the range of effects is rather small, though of course in a tight race the differences may be politically important. Finally, the effects on our Trend Estimate is detectable but does not lead to large distortions, even if we can see some noticeable differences at some times.

The charts below move though all the pollsters and plots their poll results compared to the standard trend and the trend removing house effects. Pollsters with fewer than 5 polls are all lumped together as "Other" pollsters. Once they get to our minimum number of polls, we'll have house effects for them too.

Monday, August 11, 2008

Age, Turnout and Votes

It's all about who votes. Those that do win. Those that don't lose. The chronic losers in American politics are the young who famously turn out at low rates election after election.

This year, those young people are of great interest. Allegedly they will be mobilized in huge numbers, and allegedly they will vote strongly for Barack Obama. The latest available Gallup weekly estimate (July 28-Aug 3) shows Obama leading 56%-35% among 18-29 year olds, while McCain leads 46%-37% among those 65 and older.

But will the young vote? And how much difference does it make when they don't?

The chart above shows the turnout rate by age for 2000 and 2004, based on the Census Bureau's "Current Population Survey (CPS)", the largest and best source of detailed data on turnout. The most striking result is just how low turnout is among those under 30 compared to older voters. No age group 18-29 managed to reach 45% turnout in 2000, and only two made it in 2004. Not one single age group over 30 fell so low in either year. Despite a little noise for each group, the pattern is a strong rise in participation rates with every year of age at least until the late 60s, after which there is some decline. Yet even among those 85 and over the turnout rate remains above 55%, more then 10 points higher than among their 20-something grandchildren and great-grandchildren.

The second striking feature of the chart is that the young can be mobilized a bit, under the right circumstances. Turnout among those under 30 rose significantly in 2004 compared to 2000. While turnout went up among all age groups, the relative gain was clearly greater among those under 30. While mobilizing the young is difficult, these data show that it is possible to get significant gains, at least relative to past turnout.

Even so, the "highly mobilized" 20-somethings of 2004 still fell behind the turnout of their 30-something older siblings. A supposed Obama-surge among the young may still not catch up with those even a bit older.

The irony is that the young are a large share of the population, but not of the electorate. The chart below shows the population by age in 2004 (it shifts a little by 2008 but not enough to change the story.)

The "boomers" in their 40s and 50s remain the largest group, but for our purposes there are two important points. Those under 30 make up a substantial share of the population, while those 60 and over represent a substantially smaller share at each age.

In 2004 those 18-29 were 21.8% of the population, while those 58-69 were just 13.2%. Add in the 11.5% 70 and up, and you get just 24.7% of "geezers" over 58 vs. 21.8% of "kids". But the sly old geezers know a thing or two about voting. Shift from share of the population to share of the electorate and the advantage shifts to the old: 18-29 year olds were just 16% of the electorate in 2004, while those 58-69 were an almost equal 15.9%. Add in the 70+ group at 13.4% and the geezers win hands down: 29.3% of voters vs 16% for the young. That difference is the power of high turnout. It goes a long way to explaining why Social Security is the third rail of American politics.

High turnout buys "over-representation". Divide share of voters by share of the population and you get proportionate representation. A ratio of 1.0 means a group votes proportionate to its size. Values over 1 are overrepresented groups. In 2004, for example, 55 year olds were represented 20% more than their population would suggest, with a 1.2 score. The youngest voters, 18 year olds, had an abysmal representation rate of 0.49 in 2000, less than half their share of the population.

While turnout rises with age, it is not until we hit 40 or so that we reach "fair" representation (1.0). After that, every age group is over-represented in the electorate. Less than 40, and every age group is under-represented. (Two small exceptions-- so sue me.)

So what are the implications? If you gave me a choice of being wildly popular with the young or moderately popular with the old, I'd take the old any day. They are far more reliable in voting, and while their population numbers are small they more than make up for it in over-representation thanks to turnout differences.

There is much conversation about "youth" turnout this year. Perhaps we will indeed see another rise, as we did in 2004. But unless something truly unprecedented occurs, no one can win on the young alone. The gap in turnout is simply too large.

But is age destiny? If there were constant differences in partisan preference by age, then perhaps so. But there aren't. Despite being supposedly "old and set in their ways", those 60 and up shifted their votes more than any other age group between 2000 and 2004. In 2000, the 60+ vote went to Gore by a 4 point margin. In 2004, however, those 60+ went for Bush by 8 points. That net 12 point swing, multiplied by their over-representation means a lot.

The 20-somethings also shifted, from +2 for Gore to +9 for Kerry. Coupled with their surge in turnout, the younger voters kept Kerry close in 2004 when he was losing in every other age category. But it wasn't enough to win.

The Obama campaign may be right that they can gain votes by mobilizing the young. But the old play a bigger role in elections, and they are not imovable in their vote preferences. Indeed, they make the youngest group seem a bit static by comparison. It is not the candidate's age that will be the key to winning the votes of those 60 and over. Issues and personality will play a large role. Any candidate would be well advised to recognize that the dynamic swings among older voters coupled with their substantial over-representation makes them a potent force for electoral change.

P.S. At the cross post to, Michael McDonald noticed that my plots were based on population percentages rather than percentage of citizens. That's a good catch and I probably should have used citizens in the first place. But the qualitative results don't change at all, so my story remains exactly as it is above. The precise percentages quoted do shift a little bit, but not in ways that change any of the conclusions. Therefore I've left the text above as it was, but append the first three figures, revised to include only citizens, here for completeness. Thanks to Michael for pointing this out.