1. Political Science 30: The Grammar of Hypotheses

2. Lecture Outline How to spot a theory and a hypothesis.
The grammar of a hypothesis
Independent variables
The dependent variable
Values that variables take on
Intervening variables
Confounding variables

3. 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.

4. 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?

5. The grammar of a hypothesis
Multiple Independent Variable (IVs or Xs)
IV #1
IV #2
IV #3
Just One Dependent Variable (DV or Y) DV

6. The grammar of a hypothesis
“Countries where citizens are healthy or wealthy will be less likely to experience successful revolutions.”
What are the independent and dependent variables?

7. The grammar of a hypothesis
Independent variables:
Wealth, measured by 1980 per capita GDP
Health, measured by 1980 presence or absence of universal care system
Dependent variable:
Presence or absence of successful revolution since 1980
What values can these variables take on?

8. 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)

9. 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

10. Values that the dependent variable takes on for different cases
DV Revolution. Some countries had them since 1980, some haven’t.
Haiti, Yes
Cuba, No
Spain, No
USA, No

11. 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

12. 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