[lit-ideas] Re: Polls: for future reference
- From: "William Dolphin" <dolphinw@xxxxxxxxxx>
- To: <lit-ideas@xxxxxxxxxxxxx>
- Date: Fri, 7 Nov 2008 08:22:46 -0600
The most accurate prediction of the election's outcome appears to have been
not a pollster at all but, Nate Silver, a young baseball fan whose models
for projecting results are based on algorithms he developed for fantasy
baseball. He projected the popular vote totals to within one-tenth for both
McCain and Obama. Or at least that's what it looks like now, with many
provisional and absentee ballots still to count. Silver's method takes polls
as some of the raw data, but weights them based on their performance
measuring previous races and incorporates historic voting patterns,
demographic data and a secret special sauce. You can see his work at
http://www.fivethirtyeight.com.
But to address Julie's question on how they cook up their numbers: Pollsters
make assumptions about the actual composition of the electorate on election
day -- the proportion of younger voters, Latino voters, etc. -- that may or
may not prove to be what actually happens.
Those "likely voter" models that most use are largely based on prior
elections and the stated behavior of those polled. So if you are a
56-year-old white woman with income between $75-100k who voted in 2004 and
say you are sure to vote this time, the pollster is highly likely to count
your stated candidate preference as a vote for that candidate on election
day. Conversely, if you're a 19-year-old male high school dropout making
$19k and say you'll probably vote, then your state preference may be
discounted in the computing the polls.
Even without likely voter models driving the math, any given pollster will
tend to match their polling sample to the expected composition of the
electorate, interviewing a predetermined percentage of young, old, rich,
poor, etc. If those expectations are wrong, say because a particular
candidate has energized a voting segment or because the demographics of the
electorate have changed (e.g. increased registration of Latinos or college
age folks), then the accuracy of the poll result will suffer.
Personally, I'm still scratching my head over the vote totals and procedures
in Alaska and Georgia. In Alaska, if the official tallies are to be
believed, polls showing convicted felon Ted Stevens trailing in his
reelection bid by substantial margins were wrong because voters would not
admit they intended to vote for a criminal (making Stevens the new Bradley,
I guess), and turnout was actually 20% BELOW 2004 levels, even though a
native daughter was on the top ticket. Anyone find that believable?
In Georgia, apparently the Sec. of State did not total or include or have
counted (the details are sketchy at best) the early votes cast in the metro
Atlanta counties, where 40% of voters cast ballots before election day and
Obama leads. The difference may not swing it red to blue for the
Presidential contest, and the 15 electoral votes are of little consequence
given the rest of the national map, but since I picked Georgia as my
election night Obama-shocker, I'm still holding out, yes, hope.
William Dolphin
Memphis
-----Original Message-----
From: lit-ideas-bounce@xxxxxxxxxxxxx
[mailto:lit-ideas-bounce@xxxxxxxxxxxxx]On Behalf Of Julie Krueger
Sent: Thursday, November 06, 2008 2:29 AM
To: lit-ideas@xxxxxxxxxxxxx
Subject: [lit-ideas] Re: Polls: for future reference
To what (in terms of polling tactics, etc.) do attribute that?
On Wed, Nov 5, 2008 at 10:42 PM, Eric Yost <mr.eric.yost@xxxxxxxxx> wrote:
The List: Which presidential polls were most accurate?
The Pew Research Center and Rasmussen Reports were the most accurate in
predicting the results of the 2008 election, according to a new analysis by
Fordham University political scientist Costas Panagopoulos.
The Fordham analysis ranks 23 survey research organizations on their
final, national pre-election polls, as reported on pollster.com.
On average, the polls slightly overestimated Obama's strength. The final
polls showed the Democratic ahead by an average of 7.52 percentage points --
1.37 percentage points above his current 6.15-point popular vote lead.
Seventeen of the 23 surveys overstated Obama's final victory level, while
four underestimated it. Only two -- Rasmussen and Pew -- were spot on.
http://blogs.chron.com/txpotomac/2008/11/the_list_which_presidential_po.html
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Julie Krueger
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