As most political scientists know, the outcome of the U.S.
Presidential election can be predicted within a few percentage points
(in the popular vote), based on information available months before
the election. Thus, the general election campaign for president seems
irrelevant to the outcome (except in very close elections), despite
all the media coverage of campaign strategy. However, it is also well
known that the pre-election opinion polls can vary wildly over the
campaign, and this variation is generally attributed to events in the
campaign. How can campaign events affect people's opinions on whom
they plan to vote for, and yet not affect the outcome of the election?
For that matter, why do voters consistently increase their support for
a candidate during his nominating convention, even though the
conventions are almost entirely predictable events whose effects can
be rationally forecast?
In this exploratory study, we consider several intuitively appealing,
but ultimately wrong, resolutions to this puzzle, and discuss our
current understanding of what causes opinion polls to fluctuate and
yet reach a predictable outcome. Our evidence is based on graphical
presentation and analysis of over 67,000 individual-level responses
from forty-nine commercial polls during the 1988 campaign and many
other aggregate poll results from the 1952--1992 campaigns.
We show that responses to pollsters during the campaign are not
generally informed or even, in a sense we describe, "rational." In
contrast, voters decide which candidate to eventually support based on
their enlightened preferences, as formed by the information they have
learned during the campaign, as well as basic political cues such as
ideology and party identification. We cannot prove this conclusion,
but we do show that it is consistent with the aggregate forecasts and
individual-level opinion poll responses. Based on the enlightened
preferences hypothesis, we conclude that the news media have an
important effect on the outcome of Presidential elections---not due to
misleading advertisements, sound bites, or spin doctors, but rather by
conveying candidates' positions on important issues.
Winner of the Pi Sigma Alpha Award for the best paper at the annual meetings of the Midwest Political Science Association.
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