'Leaners' and Polling Bias

Email Print


The greatest
bias in traditional political polling is the way "leaners"
are counted.

Leaners are
people who say they are undecided when polled, but when pushed to
pick someone they are leaning towards, they come up with a name,
usually someone with strong name recognition.

For example,
suppose a political poller called you and asked; “If the election
were held today, would you vote for [blank], [blank], or [blank],

Response; “I’m
not sure.”

Poller; “Well,
if you had to pick someone, who would you be leaning towards?”

Response; “Well,
er, um, I’m not sure, maybe, … , well I might pick McCain?”

Poller; “McCain?”

Response; “Yup,
McCain, I think.”

Poller; “Are
you sure?”

Response; “Yep.”

BINGO! In this
poll, the respondent will be listed as voting for McCain.

Most polls
do not list what percentage of responses are leaners except sometimes
in the fine print, but usually about 1/3 of the support of any candidate
in any poll is a leaner.

Let’s look
at a typical poll to see how the way leaners are counted distort

Anselm College Poll for New Hampshire
, October 2007, Republican


Mitt Romney
Rudy Giuliani 22%
John McCain 15%
Ron Paul 7%
Mike Huckabee 6%
Fred Thompson 5%
Tom Tancredo 1%
Sam Brownback 1%
Duncan Hunter 1%
Other 1%
None/No answer?Didn’t know 9%

[The poll does
not list a margin of statistical error. Most traditional polls have
a margin of error of 4% or less, so we will assume a 4% margin of

This poll makes
it appear that it is mathematically impossible for anyone but Romney,
Giuliani, or McCain to win, with Romney almost having it wrapped
up. The others have no chance to win.

For Giuliani,
if he takes his 22% and gets all of the 9% undecided vote, he is
still at 31%, not enough to win. So he needs the margin of error
to fall in his direction as well. Not likely.

For McCain,
if he takes his 15%, gets all 9% of the undecided vote, and the
4% margin of error falls in his favor, he will be at 28%, still
not enough to win. Unless Romney drops the 4% margin of error to
28%, then it’s a tie.

Very unlikely.

Paul has absolutely
no chance to win.

But lets look
at what would happen if the poll did not include leaners in the
candidate numbers, assuming 1/3 of all support is leaners:

Mitt Romney
Giuliani 15%
McCain 10%
Ron Paul
Huckabee 4%
Thompson 4%

If the poll
were reported this way, it would look like EVERYONE had a chance
to win. And in fact, they do, if they are able to overcome the polling
bias that leads to less media coverage for underdog candidates.
For example, in this poll, Paul would only need 1/2 of the undecided
vote to beat Romney by 3%.

The next time
you hear someone says someone has no chance to win because of a
poll, please ask them if they have analyzed the effect of leaners.

5, 2007

Lindgren [send him mail] was
the Polling Director for the 2004 Michael Badnarik Presidential
campaign, the 2004 Aaron Russo Presidential campaign, and assisted
with polling in the 2002 Ed Thompson Wisconsin Governor campaign.

Email Print