Lecture Outline

I. Building Blocks

A. “Variables” are Entities that Can

Assume DIFFERENT Values whereas “Constants” Have only ONE Value.

1. Height is a Variable because

People are of Different Heights.

Confounding variables

Building Blocks Continued

1. We are interested in Variables,

not Constants.

B. A Theory is a Relational Statement

Between Two or More Concepts which is Deductively Plausible and Empirically Generalizable.

Independent and Dependent Variables

The Independent Variable Influences the Dependent Variable (not the other way

around).

Example: The more liberal the government (independent variable) the

greater the share of income going to the

poor (dependent variable).

Lecture Outline

How to spot a theory and a hypothesis.

The grammar of a hypothesis Independent variablesThe dependent variableValues that variables take on

Intervening variables

Confounding variables

How to spot a theory and a hypothesis (definitions)

A theory is a general statement about how the world works that specifies a causal mechanism.

A hypothesis derived from this theory makes a specific prediction that can be empirically verified. It predicts that one or more causal factors will produce a single effect.

How to spot a theory and a hypothesis (for instance)

My theory is that people will be happy with their political system whenever their basic needs are fulfilled.

What are some testable hypotheses that

spring forth from this theory?

The grammar of a hypothesis -1

• Multiple Independent Variable (IVs or Xs)

IV #1

IV #2

IV #3

Just One Dependent Variable (DV or Y)

DV

The grammar of a hypothesis - 2

“Countries where citizens are healthy or wealthy will be less likely to experience successful revolutions.”

What are the independent and dependent variables?

The grammar of a hypothesis - 3

Independent variables:Wealth, measured by 1980 per capita GDPHealth, measured by 1980 presence or

absence of universal care systemDependent variable:

Presence or absence of successful revolution since 1980

What values can these variables take on?

Variables and their Values

You can think of any variable as a question:What is the average lifespan in a country?

The potential values that the variable can take on are possible answers to that question: 45.9 years (Afghanistan) 71.1 years (The Bahamas) 50.2 years (Benin) 80.7 years (Japan)

Values that Independent Variables Take on for Different Cases

IV #1 Wealth. Per capita GDP takes on different values in different countries.

Haiti $586 Cuba $3267 Spain $18,356 USA $39,678

IV #2 Health. Some countries have universal health care, some don’t.

Haiti, No Cuba, Yes Spain, Yes USA, No

Values that the Dependent Variable Takes on for Different Cases

DV Revolution. Some countries had them since 1980, some haven’t. Haiti, YesCuba, NoSpain, NoUSA, No

An Intervening Variable

It is part of the causal path that links an independent variable to the dependent variable

For this hypothesis, it could be the average citizen’s stake in the status quo, measured by how much private property the average citizen owns

Wealth Stakes

Revolution

Health

A Confounding Variable

A Confounding Variable: causes changes in the dependent variable is correlated with one of the independent variables is “causally PRIOR” to that independent variable.

Chronologically or logically, it comes first.

Wealth

Prior Current

Revolution Health Revolution