The Scientific Process

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• Research Question• Theory and Hypotheses• Research Design• Operationalization (measurement)• Empirical Observation and Analysis

II. The Research Question, Theory and Hypotheses

• Chapter 3 (JRM); • Chapters 4-5 (LeRoy – Exercises due

Monday 1/25)

Participation Quiz #1

• Directions: On a sheet of paper, answer the following questions. Be sure to include the date and your name/student number on your quiz.

• 1. What is a “dependent variable”?• 2. What is one characteristic of a good

hypothesis, according to your text?

The Research Question

• A “scientific” research question– Subject to empirical investigation– Avoid normative questions

• normative: value-laden, evaluative, “ought” or “should”, prescriptive

• Non-normative: factual, objective– Avoid purely “factual” questions– Ask questions which can be answered in

causal terms (“why” & “how” questions)

The Research Question

• A personal choice• Should be inspired by existing literature• Something “important”• Basic vs. Applied research• Most Important: Something that you find

interesting!

What is a Scientific Theory?

• A set of assumptions involving a set of interrelated concepts from which a causal statement(s) can be derived. These assumptions and causal statement(s) constitute an explanation for the phenomenon under investigation.

What is a Scientific Theory?

• “A reasoned and precise speculation about the answer to a research question, including a statement about why the proposed answer is correct.” Must have “observable implications.”

Good Theories…

• Can be generalized far beyond the specific data being analyzed

• Are not TOO abstract• Are falsifiable

Concepts and Theories

• Concepts are the “building blocks” of theories

• Def: A concept is an abstraction representing an object, a property of an object, or a certain phenomenon.

• Examples?

• Examples: Political participation, socioeconomic status, party competition, welfare generosity, level of democracy, strength of civil society, level of political violence

Example of a (Simple) TheoryWhat is the effect of negative advertising on

political participation?

• Let’s say we believe negative advertising has an impact…

• How would you put together a theory on this concept?

Higher levels of exposure to negative advertising lead to lower levels of political trust because voters gradually become disenchanted with all political candidates. As trust is eroded, we should expect to see lower levels of political participation.

Example of a (Simple) TheoryWhat is the effect of negative advertising on

political participation?

Some Important Theories in Political Science

• Costs/Benefits of Voting• The Democratic Peace• Median Voter Theory

The Calculus of Voting

• Assumptions:– Voters are rational; vote when the benefits of

voting exceed the costs• Pr(Vote) = Benefit of voting – cost of voting +

random error

Pr(Vote) = Benefit of voting – cost of voting + random error

• Hypotheses:– Turnout will be highest:

• When perceived ideological distance between candidates is large

• When perceived support for each candidate is roughly equal

• Among voters with a higher level of education• Among voters who display high levels of

attachment to the political system (trust, efficacy)

The “Democratic Peace”

• What is it?

The “Democratic Peace”• The democratic peace theory (or liberal peace theory or

simply the democratic peace) holds that democracies — usually, liberal democracies — never go to war with one another.

• They participate in wars as often as non-democracies, maybe even more often, but never with each other.

• Closest thing to a “law” that we have in international relations.

• Normative and Structural Models for why this is.

The “Democratic Peace”(from Maoz and Russett, APSR 1993)

• The Normative Model

• Observable implication:– Democracies are much less likely to go to war

with one another (although will go to war with nondemocracies)

- The longer a state has been democratized the less likely it should be to engage in conflict with another democracy or democratizing state.

• The Structural Model

• Observable implication:– Democracies are much less likely to go to war

with one another

– The more structural checks and balances built into a democratic political system (ex. presidential democracies vs parliamentary democracies), the less likely a democracy is to engage other democracies.

What explains the positions parties take during an election?

Median Voter Theory• Assumptions

– Voter preferences can be summarized as falling somewhere on a liberal-conservative (left-right) ideological scale

– In a 2-party system, voters choose the party which most closely reflects their policy preferences

– Parties are solely motivated to win elections

Median Voter Theory

• Observable Implications– In a 2-party system, the party that locates

itself closest to the median position will win– In 2-party systems, parties will compete with

one another by converging toward the median position

Theories and Hypotheses

• A hypothesis is a testable statement of causal relationship between two variables, derived from theory

• For directional variables, relationships expressed in hypotheses may be either positive or negative

Concepts vs. Variables

• Concept– Highly abstract– Can represent a variety of things

• Variable– Generally more specific/observable– Takes on at least 2 values/categories that

vary across the units/cases in our analysis

Causal Relationship

• Change in one variable causes change in another variable

Dependent vs. Independent Variable

• Dependent variable – what we are trying to explain

• Independent variable – explains variation in dependent variable

Good Hypotheses…

• Are the logical implication of the theory being tested

• Are stated in explicit, empirical terms• Can be generalized to different contexts• Are plausible• Clearly specify a relationship between an

IV & DV

Directional Hypotheses

• Apply to cases where IV and DV are orderable (directional) variables

• Positive relationship:– As one’s education increases, the probability of voting

increases– There is a positive relationship between one’s education

level and voting– As the number of different ethnic groups in state increase,

the probability of civil ware increases.– There is a positive relationship between a state’s ethnic

fractionalization and civil war.

Directional Hypotheses (cont’d)

• Negative relationship:– As the number of hours of negative ads watched

increases, the probability that an individual will vote decreases

– There is a negative relationship between exposure to negative advertising and the probability that an individual will vote

– As the level of democracy within a state increases, the probability of civil war decreases.

– There is a negative relationship between democracy and civil war.

Non-Directional Hypotheses

• Appropriate for variables that are not orderable• Hypothesis describes comparison among

categories• Examples

– Men have greater levels of support for President Bush than do women

– Whites are most likely to be Republican, while African-Americans are most likely to be Democrat

– Democracies have higher GDPs than Non-Democracies.

The Null Hypothesis

• The null hypothesis states that there is no relationship between the independent variable and the dependent variable

• Hypothesis: There is a positive relationship between exposure to negative ads and turnout

• Null hypothesis: There is no relationship between negative ads and turnout

Specifying the Unit of Analysis

• Def: “The social entities whose characteristics are the focus of study.”

• May include individuals, groups, programs, organizations and institutions, cities, states, nations, etc.

• Individual vs. Aggregate level of analysis• Ecological Inference / Fallacy• Mixing levels in a hypothesis

Unit of Analysis• Ecological Inference - The use of aggregate data to

study the behavior of individuals.

• Ecological Fallacy – Using information that shows a relationship for groups to infer that the same relationship exists for individuals when the relationship is untrue.

• Mixing Levels in a hypothesis – The more education a person has the more democratic his state is.

What is the unit of analysis?

• There is a negative relationship between the number of negative ads broadcast in a state and state turnout rate in the presidential election

There is a negative relationship between exposure to negative advertising and the probability that a person will vote.

• There is a positive relationship between the level of wealth in a country and the level of democracy

• There is a negative relationship between a basketball team’s shooting percentage and its winning percentage

• As a country becomes more democratic over time, that country becomes has increasing levels of economic development and education.

The Scientific Process

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