1. Political Science Scope and Methods Experiments in Political Science

2. Assignment: Example Enid wants to investigate the effect of saliency of message on attitude change. From an old Ph.D. she finds a swell communication on the importance of physical sciences in a liberal education. Fortunately for her, Widget University conducts separately - English classes for engineers and liberal arts majors. Within this limitation, however, the university has matched the classes carefully on age, sex composition, socioeconomic background, and College Entrance Board Scores (both verbal and mathematical ability as well as on scores in specific subjects). Enid checks on the dean's records and is happy to find that the classes have indeed been matched to the best possible extent. Enid then delivers the message to the engineers (the salient group) and to the liberal arts students (the non-salient group). The engineers show much more attitude change. Enid concludes that message saliency increases attitude change.

3. Experiments Experimentation:  Lab experiments Study of political cognition (Berinsky and Kinder)  Field experiments Effect of canvassing, telephone calls, and mailing on turnout (Green and Gerber) Effectiveness of “franking” – baby books and ballots (Cover and Brumberg)  Survey Experiments Power of Stereotypes (Berinsky and Mendelberg) War in Iraq (Berinsky)

4. Kosovo Experiment Theory: Frames as stories Hypothesis: Organization of text should affect recall and choice Treatment: ? Measures: ?

5. Wilson Candidate Experiment Theory: Stereotypes – even rejected stereotypes – are pervasive information shortcuts Hypothesis: Cuing an unacceptable social stereotype can activate an acceptable political stereotype, thereby influencing political judgments. Treatment: ? Measures: ?

6. Example: Iraq War Please give your best guess to this next question, even if you are not sure of the correct answer. As you know, the United States is currently involved in a war in Iraq. Do you happen to know how many soldiers of the U.S. military have been killed in Iraq since the fighting began in March 2003?

7. Log (Base 10) of Estimates of U.S. Troop Deaths in Iraq, 2004

8. Table 3: Predicted Probability of Causality Estimates Pr (Underestimate) Pr (Correct Answer) Pr (Overestimate) Information Low Information0.510.310.18 High Information0.360.560.07 Difference-0.15+0.25-0.11 Follow News About Iraq? Not At All Closely0.660.240.11 Very Closely0.250.670.08 Difference-0.41+0.43-0.03 Partisanship Strong Republican0.480.440.08 Strong Democrat0.350.540.12 Difference-0.13+0.10+0.04

9. Effect of Information Treatment on Support for War in Iraq Among Under-Estimators Did The U.S. Make The Right Decision in Using Military Force against Iraq? Estimate War Deaths Corrected Information Right Decision48%44% Wrong Decision52%56% N=252;  2 (1)=0.40 Pr=0.53 Has The Current War in Iraq Been Worth Fighting? Estimate War Deaths Corrected Information Worth Fighting58%53% Not Worth Fighting42%47% N=253;  2 (1)=0.71 Pr=0.40

10. Among Over-estimators Did The U.S. Make The Right Decision in Using Military Force against Iraq? Estimate War Deaths Corrected Information Right Decision42% Wrong Decision58% N=57;  2 (1)=0.00 Pr=0.95 Has The Current War in Iraq Been Worth Fighting? Estimate War Deaths Corrected Information Worth Fighting42%48% Not Worth Fighting58%52% N=57  2 (1)=0.26 Pr=0.61