Likely Voters I: Thanks Harris

Legacy blog posts Likely Voters

So on to likely voter models. Finally.

I am in the process of gathering information on the likely voter screens and models used by most of the major national polls. Over the next few days, I will be posting more than you ever wanted to know about how pollsters pick likely voters. And on the eve of this effort, one major polling organization released a survey that illuminates one of the most important issues in the likely voter debate.

But first, a little background. Over the last few days, two polls released subgroup results among voters who say they will cast their first presidential ballots in this election. The Newsweek survey, released over the weekend, found that 15% of registered voters and 9% of likely voters say they will cast their first vote for president ballot in 2004. Notably, these first-time likely voters prefer John Kerry to George Bush by a 21-point margin (57% to 36%).

On Tuesday, the ABC Polling Unit found a similar number of likely voters (10%) reporting that 2004 would be their first presidential vote. They also preferred Kerry, but by a narrower margin (54% to 43%). The ABC analysis includes other helpful details: The overwhelming majority (80%) of first-time voters are under 30 years of age. They tend to be lower income, less well-educated and more often minority than repeat voters.

The ABC release also noted that Kerry’s 11-point margin among new voters is “about the same as Al Gore’s margin among first-timers, nine points, in 2000” (the 2000 result comes from exit polls). They also report that the percentage of first time voters in their sample of likely voters (10%) is roughly comparable to percentage of first timers in the 2000 exit polls (9%).

As I write about likely voter models over the next few days, one issue will be most important: Will turnout among first time voters be significantly higher this year and will the likely voter models catch such an increase if it occurs? The share of first-time voters projected by the ABC and Newsweek likely voter models is no different than in 2000, even though ABC notes in its release that “turnout overall is looking to be up: Sixty-two percent of likely voters are following the race very closely, up 20 points from this time in 2000, and Americans are four points more apt to say they’re registered to vote.”

In gathering information about likely voter models over the last few days, I have heard rumblings that some organizations are experimenting internally with tweaks to their models to accommodate the higher expected turnout. Unfortunately, the details of their efforts are mostly hidden from public view.

Then yesterday, Harris Interactive did something truly remarkable. They released data from their most recent telephone survey that included results for two different likely voter models. Collectively, these two models represent the two competing philosophies for selecting likely voters that I will be discussing over the next few days. I’ll let the Harris release speak for itself

Using one definition of likely voters, those who are registered to vote and are “absolutely certain” to vote, the poll shows President Bush with a modest two-point lead (48% to 46%). Using this definition but excluding all those who were old enough to vote in 2000 but did not do so, President Bush has a commanding eight-point lead (51% to 43%). This second definition has proved more accurate in the past, but there are some indications that in this election many people who did not vote in 2000 will turn out to vote, in which case it would be wrong to exclude them.

Harris has just provided a big clue to why some of the polls — those using the more traditional likely voter models — may be showing President Bush with a 4-6 point lead, while others show a much closer race. When their definition of a likely voter includes only those who report voting in 2000, Bush’s lead is much wider than when they include the 2000 non-voters. When their definition of a likely voter excludes those who voted in 2000, the Bush lead is mch wider than when they do not.

What Harris did today is highly unusual, because it breaks with a longstanding tradition among media pollsters of reporting a single, unshakable projection of “likely voters.” Harris is doing what internal campaign pollsters have done for years — conceding (perhaps just for the moment) that we cannot project turnout with certainty and reporting a range of potential results. Bravo to Harris!

[10/21: Typo corrected above – twice! – thanks to alert readers JB and bravenewworld. Link repaired – thanks David

Mark Blumenthal

Mark Blumenthal is political pollster with deep and varied experience across survey research, campaigns, and media. The original "Mystery Pollster" and co-creator of Pollster.com, he explains complex concepts to a multitude of audiences and how data informs politics and decision-making. A researcher and consultant who crafts effective questions and identifies innovative solutions to deliver results. An award winning political journalist who brings insights and crafts compelling narratives from chaotic data.