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Lecture Outline

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.

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Lecture Outline

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  1. 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

  2. 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.

  3. 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).

  4. 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

  5. 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.

  6. 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?

  7. 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 -1

  8. 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?

  9. The grammar of a hypothesis - 3 • 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?

  10. 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)

  11. 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 Independent Variables Take on for Different Cases

  12. 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

  13. 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

  14. 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

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