American Government
Public Opinion
Two Ways to Measure Public
Opinion
• Intensity—how strongly people feel.
• Representativeness—how widespread a
particular belief is held.
Measuring the Intensity of Public
Opinion
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•
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Ask your family and friends
Count people at demonstrations
Track communications to elected officials
Count membership in interest groups
Voluntary polls: www.vote.com
Measuring the Intensity of Public
Opinion
• Before the advent of scientific polling:
– Information supplied by editorials,
pamphleteers, local leaders
– Straw polls
– These methods were badly biased
Straw Polling
• Literary Digest conducted “presidential
preference poll” in 1936
• Mailed 10 million ballots to car owners and
phone customers
• Prediction: Alf Landon (R) would beat FDR
• Actual outcome: FDR won by 20%
Why the Discrepancy?
• Sample was not representative of the
voting population
• Selection mechanism was correlated with
voting preference
– Cars and phones = luxuries (in the 1930s!)
– People who owned these items were mostly
Republicans
Scientific Polling—A
Representative Measure
• A poll with fewer respondents can be
much more accurate
• Basic techniques:
– Random sampling
– Bigger sample = better (up to a point)
• Sample size of 100 yields margin of error +/- 5%
• Sample size of 1000 yields margin of +/- 3%
Random Sampling in Action
Final Gallup Presidential Poll vs. Actual Outcome
Year
2004
2000
1996
1992
Party
D
R
D
R
D
R
Reform
D
R
Indep
Final Gallup
49
49
45
47
52
41
7
44
37
14
Actual
48
51
48
48
49
41
8
43
38
19
Error
+1
-2
-3
-1
+3
0
-1
+1
-1
-5
How Accurate are Opinion Polls?
• Sampling error
– Reflects random differences between sample
and entire population
• Systematic error
– Ex: leading questions
How is this question biased?
Sierra Club: “Our nation is still blessed with
millions of acres of public lands, including
road-less wilderness areas, forests, and
range lands. Land developers, loggers
and mining and oil companies want to
increase their operations on these public
lands. Do you think these remaining
pristine areas of your public lands should
be protected from such exploitation?”
How is this question biased?
National Right to Work Committee (antilabor union): “Are you in favor of allowing
construction union czars the power to shut
down an entire construction site because
of a dispute with a single contractor, thus
forcing even more workers to knuckle
under to union agents?”
“Push Polls” in Presidential
Nominating Contests
• In 2000, voters in South Carolina were
asked: "Would you be more likely or less
likely to vote for John McCain for president
if you knew he had fathered an illegitimate
black child?"
Uninformed Responses
• Even well-intentioned pollsters can run
into this problem
• People feel obligated to give an answer
• National Affairs Act Poll
– "Some people say that the 1975 Public Affairs
Act should be repealed. Do you agree or
disagree with this idea?”
Should We Ignore Public Opinion
Entirely?
• If large segments of the public:
– Are politically ignorant
– Hold inconsistent views, and
– Can be manipulated by varying the words or
context of questions
• How can public opinion play its assigned
role in democratic politics?
Is Public Opinion Meaningful?
• Yes—in the aggregate if not always at the
individual level
• The sum of the public’s attitudes is both
stable and coherent
Stability of Aggregate Public
Opinion
Opinion Responds to Changing
Conditions
Explaining Aggregate Stability
• Measurement errors and random
individual changes cancel each other out
– The average remains the same if
circumstances remain the same
• Opinion leadership
– Provides cues and information
– Means for uninformed/inattentive to free ride
• Let's say you're a politician who is trying to commission a
poll to determine whether the public supports a new
program to provide down payments for first-time car
buyers. Let's assume 30 percent of the public plans to
buy a first car and would support the program no matter
what; 40 percent already owns a first car but would
support the program if it doesn't cost more than a buck a
month in additional taxes; and 30 percent thinks the
roads are crowded enough as it is and would oppose the
program no matter what.
• Group 1: How would you design a public opinion
question to maximize support for the program?
• Group 2: How would you design a public opinion
question to minimize support for the program?
• Group 3: How would you design a public opinion
question to minimize bias in either direction?