Data

1. Data An Introduction to Data and Statistics

2. Does aspirin help prevent heart attacks? • How did they assign aspirin versus placebo? • People were able to choose. • They assigned pills randomly. • Because of medical ethics, they gave aspirin to people at greater risk for heart disease.

3. Does green tea prevent cancer? • Let’s say we find that people who drink green tea are half as likely to get lung cancer? What can we conclude? • People who smoke are less likely to drink green tea to prevent cancer. • People who drink green tea may lead healthier lives in general, preventing lung cancer. • We should start a government campaign to get people to drink more green tea.

4. Flip a coin 1000 times • Is it possible for there to be 5 heads in a row? A. Yes, B. No • Is it possible for there to be 100 heads in a row? A. Yes, B. No • From mathematical theory, can we estimate how likely it is to get 100 heads in a row? A. Yes, B. No

5. What do statistics do? • Describe • Approval rating of Obama • Support for health care reform • Answer questions • What causes people to support Obama? • What causes people to support war?

6. Description versus Prediction • Journalists describe • 53% approval rating for Obama • 53% support gun control

7. Description versus Prediction • Political scientists predict, explain • Factors associated with support for Obama, like support for health care, or support for taxing the rich • Predict election outcomes, by knowing unemployment and inflation

8. Description • Data used to describe come from random samples • Then, we make inferences from samples to populations • This inference is based on statistical mathematical theory • We will not be learning the mathematics of this theory – we will assume them

9. Prediction, explanation • Data used to describe come from random samples • We choose populations to generalize from: • Students • Victims of violence • We infer which factors predict something

10. Rosencrantz & Guildenstern Are Dead • http://www.youtube.com/watch?v=RjOqaD5tWB0

11. Normative … …statements usually are statements of opinion that give clues about the speaker’s personal value biases. They often have the word “should” in them. Remember if there is any element of normative bias in the statement, then it is normative. If it requires the assumption that the reader agrees with the values of the author, then it is normative.

12. Interpretive … … statements are when people are interpreting a text. The text could be a Constitution, the Bible or a work of political philosophy. People can interpret texts in certain ways that may emanate from their biases, but nonetheless could be a valid interpretation. Interpretive statements are different from empirical statements because interpretive statements must be falsifiable – in other words, they must be able to be wrong.

13. Empirical … …statements are 100% verifiable. They are facts. Factual statements may not be true. But it would be 100% verifiable to find out whether they are true or not. The difference between empirical statements and causal statements is that factual statements are verifiable events. They are either 100% true or 100% false. At times, the difference between the two will be a judgment call based on how much agreement there is likely to be about the statement. If there is absolute widespread agreement, it is a fact. “Booth killed Lincoln in the theater” is a fact. You could also say that Booth’s gun caused Lincoln’s death and this would be an empirical statement despite the word cause in the sentence.

14. Causal… …statements would require going out into the world and testing whether something causes something else through observation. “Public opinion causes changes in the ideological nature of Supreme court opinions” is a causal statement because we could go out and get measures of public opinion and Supreme Court outcomes and see whether there is a correspondence. This would be testing a causal claim. Causal claims must be falsifiable – like interpretive statements – but causal claims are also testable by collecting data. You should not be distracted by notions that the phenomena that are causally connected would be difficult to measure. If you can imagine a way to measure the two phenomena that may be causally related, then they are probably measurable.

15. Causality • Something that varies across some units causes something else that also varies across the same units • Can be measured quantitatively (even if this is measured as low, medium, high)

16. Causal arguments? • The liberalism of the Supreme Court caused the health care decision. • The ideology of nominating presidents affects the ideology of Supreme Court justices. • Levels of saturated fat in the diet causes an increased probability of getting heart disease. • Cancer caused John’s death.

17. Example statements • People who racially stereotype cause a great deal of harm.

18. Example statements • People who racially stereotype are less likely to support the rule of law.

19. Example statements • Weingast says “stable democracy does not simply arise because some countries happen to have the relevant shared set of values” and that “the relationship between citizen values and democratic stability is not a causal one.” • (Helpful hint: is the writer of this sentence interpreting what Weingast is saying?)

20. Example statements • National standards for religious freedom must be developed.

21. Example statements • Gibson argues the anti-coup demonstrations in Russia in the early 1990s are best explained by people acting on social incentives to oppose the coup. Therefore, he would probably argue that social identity is most prevalent for political participation.

22. Example statements • When the Supreme Court is too liberal, this leads to a whittling of respect for the rule of law.

23. Example statements • When a government supports the religion of the majority, this leads to oppression of minorities.

24. Example statements • Perceived political disadvantage causes people to feel helpless – like they have no control over their lives.

25. Example statements • People who are already angry about their powerlessness in a society are more likely to challenge their government in the face of a grievance.

26. Example statements • There is too much reading in Dr. Baird’s class.