Choosing Research Designs I

1. Choosing Research Designs I Experimental and Quasi-Experimental

2. Experimental Designs • Experimental research design: The researcher has control over the experiment in terms of sample selection, treatment, environment, etc. • Experimental designs are typical in psychology, medicine, education, etc.

3. Experimental Designs Experiments often discuss pre and post test observations • POST-TEST ONLY X O 1 Where: 0t = Observation in time t of experimental group X = Treatment 0c = Control group

4. Experimental Designs • PRE-TEST POST-TEST O1 X O2 Note how the above test includes no control group. What is a control group and why include it? • PRE-TEST POST-TEST WITH CONTROL GROUP O1 X O2 O1 O2

5. Key question of Internal Validity • When we test a hypothesis and either accept it or reject it, how do we know that we made the right decision? • What about alternative explanations that we did not account for? • What should we do to gain confidence?

6. Internal Validity • Are there other causes for what I am observing? • If so, a study will lack internal validity if it cannot rule out plausible alternative explanations.

7. Internal Validity of a Study • What you measured and what you saw? • Your program and your observations? Is the relationship causal between... Alternative cause Alternative cause Research Project Observations Program-outcome Relationship What you do What you see Alternative cause Alternative cause Observation In this study

8. DID YOU FIND THAT BORING?THEN HOW ABOUT A JOLT OF CUTENESS!

9. Experimental Designs • What do you do if you fear that your simple pre and post test single observations are atypical? • CONTROL WITH MORE OBSERVATION IN THE PRETEST O1 O2 O3 X O4 O1 O2 O3 O4

10. Experimental Designs • Of course, we could also experiment to see if removing a factor has an effect instead of adding a treatment factor • PRE-TEST POST-TEST REMOVING THE TREATMENT _ O1 X O2 X O3 X 04

11. Experimental Designs Research design with more power to control for time • Pre-test post-test O1 O2 O3 X O4 O5 O6 • Pre-test post-test with control group O1 O2 O3 X O4 O5 O6 O1 O2 O3 O4 O5 O6

12. Did you bring your lab coat? • Considering true experiments are close to impossible or unethical in political science, we need to apply science differently. • Hence, this is why we in political science often use Quasi-experimental or non-experimental research designs

13. Quasi-Experimental • Quasi-experiments: The researcher does not have control over the experiment, rather the experiment occurs in a “natural” setting. • Quasi-experimental design are typical in economics, sociology, public administration, urban planning, political sciences, etc.

14. Quasi-Experimental • A prominent example of this type of research is arguably by Samuel Huntington, who argues that Latin American immigration, especially Mexican, is altering US culture for the worse. • He essentially predicts that the United States will be a divided, less productive, society, ruining the past culture that has made the United States great. http://www.foreignpolicy.com/story/cms.php?story_id=2495

15. Quasi-Experimental Huntington points out the following X variables: • Proximity of Mexico, Latin America to USA • Former ties to Mexico • Magnitude of recent wave of immigration • Duration of recent wave of immigration • Illegality He does this by observing what is going on today. It is crucial that one understands his assumptions and evaluates what he claims as evidence for his theory