1. Jan. 23 Statistic for the Day: Average Number of Times an American Opens the Refrigerator Each Day: 22 Assignment: Having read Chapter 9, go back and study it closely. Exercises p153-155: 1, 2, 4, 5, 9 These slides were created by Tom Hettmansperger and in some cases modified by David Hunter Source: Harper’s Magazine

2. Recall Research Question or Hypothesis Research Question or Hypothesis Quantification Quantification Collect data Collect data Analyze data Analyze data Conclusions and/or action Conclusions and/or action

3. As first step in extracting information from data use graphics or pictures: Boxplot Boxplot  Stem and leaf  Median and quartiles Histogram or normal curve Histogram or normal curve  Mean and standard deviation

4. Boxplot

5. Overlapping Histograms

6. Histogram with Normal Curve

7. Scatter Plot for two measurements: RELATIONSHIP

8. US Pop and Violent Crime Table 9.2 p155 text Year198219831985198619871988198919901991 US Pop 231234239241243246248249252 No. crimes 1.321.261.331.491.481.571.651.821.91 In millions

10. If we want to suggest a much more dramatic increase:

11. Enrolment in higher education As percent of population

13. Moral of the story: Whenever you meet a graph that is very far from square, it is likely to produce an impression different from what you would have obtained from the data themselves.

14. Almost any graph in which the vertical scale does not start with zero is deceptive. Another moral:

15. This Is a Good Bar Graph

16. BAD

17. The problem with the pens is that it is the heights that should be compared. But instead, we end up comparing the areas. The areas do not make the correct comparison.

18. GOOD But with an error

19. The letters are good because each letter represents an amount. However, one should use the correct number of letters

20. Bogus vertical scale. Hard to say what the graph should look like.

21. Portion of income taken by the government. Top: spending equal to the income in western states. Bottom: more densely populated east.

22. Some people think it means that rhinos have gotten smaller!