Chapter 3: Explanations, Hypotheses, and Making Comparisons

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Chapter 3 Explanations, Hypotheses, and Making
Comparisons
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Preliminaries

• In previous lectures you learned that political
  science research starts with defining and
  measuring concepts.
• Measurement entails
• Defining the concept to be measured clearly.
• Accurate measurement of the concept.
• Selecting variables or indices to accomplish that
  measurement.
• The measurement process is intended to identify
  clearly what it is you want to study, and then
  obtain empirical data which represents that
  concept.
• However, the process does not stop here.
• We need to propose and test explanations for the
  political phenomenon we want to study.
• Here the concern is over why relationships
  might exist among our research concepts.

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Elements of Explanations

• Any explanation for research concepts entails
  explaining variation and covariation.
• If a concept y varies, why does it vary?
• Does y covary with another concept x?
• As political scientists, we seek to understand
  differences, variations, and covariations?
• Examples
• Why do people in the United States turnout/not
  turnout to vote?
• Country 1 has more democratic institutions than
  country 2. Why?
• Some people are opposed to abortion on demand?
  Why?
• Some states place more restrictions on abortion
  than others. Why?
• Some people turn out to vote, while others do
  not. Why?
• Public liberalism and conservatism can be shown
  to vary through time. Why?
• Presidential approval ratings rise and fall
  through time. Why?
• Some people think it would be a good idea for
  college students to be able to carry concealed
  weapons on college campuses. Others do not. What
  explains these differences?

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• Good explanations describe a connection between a
  dependent variable and a causal variable. A
  causal variable is also called an independent
  variable.
• Example
• Support for concealed weapons on college campuses
  is a function of peoples partisanship.
• Good explanations provide a direction for
  relationships.
• Example
• Support for concealed weapons on college campuses
  is higher among Republicans than it is among
  Democrats.
• Good explanations should also be testable.
• Example
• Do an opinion survey among the general
  population. Construct a measure of support for
  concealed weapons on college campuses. Record the
  respondents partisanship during the survey. We
  should find covariation in the expected direction
  if the explanation is true.
• Is this explanation exhaustive? Are there some
  other reasons people might support or not support
  concealed weapons on college campuses.

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Hypotheses

• An hypothesis is a testable statement about the
  empirical relationship between an independent
  variable and a dependent variable.
• An hypothesis tells us how different values of a
  dependent variable should be related to values of
  an independent variable.
• Examples
• Explanation Support for gun regulation is a
  function of partisanship.
• Hypothesis Support for concealed weapons on
  college campuses should be higher among
  Republicans than among Democrats.
• Explanation Voter turnout is a function of voter
  demographics
• Hypothesis Voter turnout should be higher among
  older people than it is among younger people.
• Hypothesis Voter turnout should be higher among
  better educated people than among lower educated
  people.
• Hypothesis Voter turnout should be higher among
  people with high incomes than among people with
  low incomes.

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• Why do some people favor candidates or policies,
  while others disfavor certain candidates or
  policies? Competing theories.
• Rationality - People favor policies and/or
  candidates that promote their own personal
  self-interest.
• Hypothesis Voting Republican should be greater
  among those with higher income.
• Hypothesis Voting for the incumbent candidate
  should depend on the individuals personal
  financial situation in the recent past.
• Hypothesis Non-support for efforts to slow
  global climate change should be greater among
  those who work in industries which pollute the
  environment.
• Sociotropic - People favor policies or candidates
  that maximize social welfare.
• Hypothesis Support for environmental regulation
  should be greater among those whose values are
  communitarian, rather than individualistic.
• Hypothesis People who view the economy as a
  whole as performing well, regardless of their own
  financial situation, are more likely to vote for
  the incumbent candidate.
• Hypothesis Cross-nationally, countries having
  values more supportive of equity should be more
  supportive of programs to help the poor.

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Testing Hypotheses with Descriptive Statistics or
Comparisons

• We can easily use the tools you have learned up
  to now to construct some basic tests of
  hypotheses.
• However, note that these are very basic tests
  which do not provide measures of certainty about
  the hypotheses.
• Examples

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Hypothesis Smoking is a function of ones income
level (a proxy for health sophistication).
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Hypothesis A higher level of economic
development produces greater support for civil
liberties. (Or, does the relation run in the
other direction?)
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Hypothesis Students who study more perform
better in their courses.
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Hypothesis Voter turnout is higher among older
people than it is among younger people.
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Hypothesis Political Activists are more likely
to turnout to vote.
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Hypothesis Collective bargaining bolsters
economic welfare for the middle class.
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Hypothesis Support for gun control is higher
among Democrats than among Republicans.
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Hypothesis Smoking is higher among low income
groups (a proxy for health sophistication).
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Hypothesis A higher level of economic
development produces greater support for civil
liberties. (Or, does the relation run in the
other direction?)
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Hypothesis Collective bargaining bolsters
economic welfare for the middle class. Same as
before using group percentages, rather than a
graph.