Poll of Polls

Divergent Polls Interpreting Polls Legacy blog posts The 2004 Race

Alert reader JM tipped me off to the fact that Bill Schneider has reprised his “poll of polls” summary on CNN’s Inside Politics. According to the transcript, Schneider combined the results of five surveys released this week by Gallup, ABC News, Investor’s Business Daily/TIPP, Time and Newsweek and showed George Bush ahead of John Kerry by an average of five points (50% to 45%). Fair enough. But then Schneider added this: “Last week’s poll of polls showed Bush just one point ahead.” The contrast certainly implies a big shift in Bush’s favor.

Now, I’m glad that CNN is willing to look at a broad cross-section of surveys rather than focusing exclusively on the Gallup survey they sponsor with USA Today. I have certainly urged readers to average polls as a way of reducing random variation, although I have emphasized averages that make apples-to-apples comparisons over time. Unfortunately, Schneider’s two weekly averages were not comparable. I do not know which surveys he used last week (and I can find no reference to a “poll-of-polls” in the Inside Politics transcripts from last week), but they were certainly different since neither Time nor Newsweek released surveys last week.

Has there been a sea change in the race over the last week? The Gallup/CNN/USA Today poll certainly suggests as much, having flipped in just one week from a one-point Kerry lead (49% to 48%) to an eight-point Bush blowout (52% to 44%). This Gallup result gets support from the latest Newsweek survey, which shows Bush with a similar six-point lead among likely voters (50% to 44%; although the last Newsweek survey, conducted just after the first debate, did not report results for likely voters).

However, consider the following survey results for likely voters released in the last few days compared to comparable surveys from the previous week (except Time, which was conducted 10/6-7; all are based on vote questions that include Ralph Nader).

Only the IBD/TIPP survey shows a slight, but statistically insignificant increase in Bush’s lead, from one point (45% to 44%) to three points (47% to 44%) over the last week. [These results are for the two-way vote question without Nader — see note below]

Others show no change or statistically insignificant movement to Kerry:

  • ABC News – Bush lead goes from four points (50% to 46%) last week to three points (50% to 47%) today.
  • CBS News – goes from a three-point Bush lead (48% to 45%) to a two-point Bush lead (47% to 45%)
  • Time – Bush’s retains a one one-point (46% to 45%) although both candidates gained (48% to 47% reported 10/6-7)
  • Zogby – reported a 45%-45% dead heat on October 13 and the same 45%-45% margin yesterday.
  • The Rasmussen automated surveys have gone from 47%-46% Bush lead reported October 12 to a 47%-47% dead heat yesterday.
  • The Democratic polling group Democracy Corps shows Kerry gaining, going from a 48%-48% dead heat to a 50% to 47% Kerry advantage.

(All of the numbers are available at the Polling Report and Rasmussen Reports).

So what about the Gallup and Newsweek surveys? As I will describe in much more detail in a few days, both appear to use a very similar method to identify “likely voters,” a method that has been the object of much criticism and debate. As Ruy Teixeira and Alan Abramowitz have pointed out (and I agree with them on this point), among registered voters, both surveys show much less change:

  • The Gallup survey went from showing an even race last week (48% to 48%) among registered voters to a three-point Bush lead (49% to 46%) now
  • The Newsweek survey went from a two-point Kerry advantage over the weekend following the first debate (49% to 46%) to a one point Bush advantage now (48% to 47%)

So consider a different set of averages that makes an apples-to-apples comparison using all nine of the surveys mentioned above, substituting results among registered voters for likely voters for Gallup and Newsweek. Before last week’s debate, Bush led by one point (47% to 46%). Now he leads by two (48% to 46%). That’s a gain for the President, but a very small one.

[Update: In citing results from the IBD/TIPP poll above, I inadvertently used the Bush-Kerry two-way vote question above. The change on the question that includes Ralph Nader was even smaller over the last week, Bush’s lead grew from three points (47% to 44%) to four points (49% to 45%) over the equivalent days. Note that this morning’s release from TIPP has the margin closing slightly: Bush ahead by two on the 3-way choice (48% to 46%, 2% for Nader) and dead even (45% to 45%) on the 2-way choice)]

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.