Transcript Forecasting the 2008 National Elections James Campbell PS

Forecasting the 2008 National Elections
James Campbell
PS: Political Science and Politics
October 2008
The 2008 National Elections
Forecast Models: Challenge of 2008
The 2008 election should be easy to forecast, but for a variety
of reasons it poses challenges for the researcher.
Unique Features of the 2008 Election:
1) It is an Open-Seat: No Incumbent, No VP (first time in
60
years). Such race are more competitive
2) Contentious Democratic Primary
3) A Maverick Republican Candidate: John McCain
4) Obama the first African American to win the
nomination
of a major party.
The 2008 National Elections
Open-Seat: Reasons for Competitiveness
Open-seats are thought to be more competitive is that they
are less “retrospective” than races with either an
incumbent or VP in the race.
Retrospective Voting:
The conventional wisdom is that presidential elections
are referendums on the in-party or incumbent party.
The 2008 National Elections
Contentious Primaries:
The competitive strength of a candidate can often be
diminished by a bruising primary fight. It was unclear in
how the tough Democratic primary battle between Clinton
and Obama would impact his candidacy.
Race and the Election:
Will race be a net asset or a net liability for Obama?
The 2008 National Elections
Evaluating the Forecasts:
How do we properly evaluate the forecasts after the election?
All Forecasts are Imperfect
Despite inherent imperfections, forecast can not only be
evaluated they often quite accurate.
The 2008 National Elections
Evaluating Forecasts: Benchmarks 1948-2004:
Naïve Forecasts:
Mean Absolute Error:
National Vote will split evenly
4.5
In-Party will win a predictable
share of national vote
4.5
Prediction based on polls at
Labor Day
4.3
Prediction based on polls after
Convention
3.7
Polls Week Before
2.3
Election Day
2.0
The 2008 National Elections
Scholar
Forecast
Terms
Campbell
Polling, GDP,
convention
bump
Abramowitz
Holbrook
Predicted
Two Party
Vote
(McCain)
Days Before
Election
Chance vote
is < 50% for
candidate
52.7
57
83 % (McCain)
Approval
Rating, GDP,
in-party status
45.7
69
90% (Obama)
Approval
Rating, Econ
sat., open seat
44.3
60
92% (Obama)