1. Political Science 30: Political Inquiry

2. Qualitative Research Design II Selecting on the Dependent Variable Mills’ Method of Agreement Mills’ Method of Difference Examples Clem Miller Dreze and Sen

3. Selecting on the Dependent Variable Selecting cases according to the value of the dependent variable that they take on is more controversial than selecting on the independent variable. It allows you to look at extreme values or divergent cases. “However, if this design is to lead to meaningful … causal inferences, it is crucial to select observations without regard to values of the explanatory variables. K.K.V.”

4. Selecting on the Dependent Variable: Method of Agreement When you use Mills’ Method of Agreement, you select cases that take on the same values of the dependent variable. This helps you to rule out possible causes, because independent variables that vary over these cases can’t cause the dependent var. This method can only disprove a hypothesis, because it can’t find a correlation.

5. Selecting on the Dependent Variable: Method of Agreement This design could help us rule out “early industrialization” as a cause of whether a country has a viable socialist party. CaseEarly Industrialization? Viable Socialist Party? FranceNoYes BritainYes

6. Selecting on the Dependent Variable: Method of Difference When you use Mills’ Method of Difference, you select cases that take on different values of the dependent variable. After you have selected your cases, you determine what values they take on for some independent variables. Perhaps one independent variable will vary across your cases, and explain the D.V.

7. Selecting on the Dependent Variable: Method of Difference Adding a country that has no viable socialist party can add causal leverage to our early investigation. CaseEarly Indust.?Feudalism?Viable Social Party? FranceNoYes BritainYes USAYesNo

8. Example: Clem Miller This Congressman writing home to his supporters tells the story of two different lobbying efforts on behalf of farmers. Let’s assume that his process of case selection came in the same order that his narrative is written. If so, he selected on independent variables and used the “Most Similar Systems” design.

9. Example: Clem Miller CaseEconomic Trouble? Sympathy of Officials? Well Organized? Govt. Help? Walnut Growers Poultry Men

10. Example: Dreze and Sen Both countries began a new political regime at mid-century with large populations and little wealth. They have diverged since then: “There is little doubt that as far a morbidity, mortality, and longevity are concerned, China has a large and decisive lead over India. (p. 205)” “What has brought about that lead is a matter of very considerable interest. (p. 206)”

11. Comparing Many Research Methods: Measurement Validity Measurement validity judges the gap between your conceptual definition and your operational definition. Qualitative – Highest measurement validity The measurement validity of other research methods (Lab experiments, quasi/natural experiments, and quantitative research) really depends on what you are trying to measure.

12. Comparing Many Research Methods: Internal Validity Internal validity judges how well a research design has tested a causal relationship, in the cases examined. Random assignment is the key. Lab Experiments – highest Quasi/Natural experiments – medium Qualitative research – medium Quantitative research – lowest

13. Comparing Many Research Methods: External Validity External validity is how confident we can be that a causal relationship identified in our cases can be generalized to the outside world. Random sampling is key Quantitative research – highest Quasi/Natural experiments – medium Lab experiments – low Qualitative research – low

14. Comparing Many Research Methods: Overall Lessons The best research design depends on your research question and the particular problems that it poses. The best research uses a mixture of methods to test a hypothesis.