Study C Many political scientists predict election outcomes for fun. It turns ou
ID: 3368877 • Letter: S
Question
Study C
Many political scientists predict election outcomes for fun. It turns out that with a handful of variables, it is possible to estimate the two-party vote share of an election years out. For instance, a model accounting for only GDP growth rate in the first quarter of the election year and whether the sitting President is running again will yield fairly accurate in its forecasts. The table below presents the results of a linear regression model predicting two-party vote share (100 = incumbent party received all the votes; 0 = incumbent party received no votes; 50 = the two parties split them equally).
Variable
Model #1
Model #2
Q1 GDP growth
(percentage points)
2.0
(0.4)
1.0
(0.25)
Incumbent Running
(0 = No; 1 = Yes)
6.0
(0.5)
Constant
48
(3.0)
45
(2.0)
N
18
18
R-sq
0.30
0.63
Numbers in parentheses represent standard errors.
According to Model #1, what is the relationship between first quarter GDP growth and two party Presidential vote share?
According to Model #2, what is the relationship between first quarter GDP growth and two party Presidential vote share?
How much more predictive of Presidential vote share is Model #2 than Model #1?
In 2016, the incumbent President was not running and first quarter GDP growth was 0.7 percentage points. What was Hillary Clinton’s expected vote share according to Model #2?
What variables would you add to the analysis to predict vote share and why?
Variable
Model #1
Model #2
Q1 GDP growth
(percentage points)
2.0
(0.4)
1.0
(0.25)
Incumbent Running
(0 = No; 1 = Yes)
6.0
(0.5)
Constant
48
(3.0)
45
(2.0)
N
18
18
R-sq
0.30
0.63
Explanation / Answer
1. According to the Model #1, for every 1 percent point increase in GDP, the vote share of Incumbent party increases by 2 percentage points. Vote share of the other party decreases by the same amount.
2. According to Model#2, for every 1 point increase in GDP, the vote share of Incumbent party increases by 1 percentage point. Vote share of the other party decreases by the same amount.
3. Model one explains only 30% (R -sq) of the presidential vote, whereas model 2 explains 63%
4. According to model 2, if the incumbent is not running and GDP growth = 0.7
Model : Incumbent vote share = Const + b1*GDP + b2* incumbent running.
Hillary Clinton vote share = 45 + 1*0.7 + 6*0 = 45.7%
5. The other factors could be 1. people perception of corruption on incumbent party, 2. successful policies, 3. Employment growth etc., the factors which can influence the public decision on Voting.