1. Warm-up
A study of the size of jury awards in civil cases (such as injury, product liability, and medical malpractice) in Chicago showed that the median award was about $8,000. But the mean award was about $69,000. Explain how this great difference between the two measures of center can occur.

2. Section 1.2 Comparing Distributions

3. Comparing Distributions
Often, the question of interest is which car/drug/fuel additive etc. is preferable. In this case, we need to be able to compare distributions.

4. Graph Choices for Comparing Distributions
For categorical variables, a side-by-side bar graph works well.

5. Graph Choices for Comparing Distributions
For two small quantitative data sets, a back-to-back stem and leaf plot is effective.

6. Graph Choices for Comparing Distributions
Boxplots alone contain little detail, but side-by-side boxplots effectively compare large sets of quantitative data.
The plot is useful for showing the comparison of several groups. This example shows a fat absorption test in patients who have AIDS, AIDS Related complex, are HIV positive but asymptomatic, and normal controls:

7. Fat Absorption

8. Keys to Remember Plot both distributions using the same scale.
Always compare apples to apples. By that, I mean compare mean to mean, median to median, Q1 to Q1, etc. Students lose points on the AP exam when they make comparisons between two different measures.

9. Now let’s compare…
Fat Absorption

10. Study habits and attitude test scores for freshmen men and women.
154
137
152
101
126
165
200
109
115
140
178
103
129
148
Men
108
114
180
126
169
109 75
113 70
187
140 91
115 92
146
132 88
151
104
Draw a graph of the distributions, then compare men and women’s SSHA scores. Does this data support the argument that women study more than men?
If another woman was added to the appropriate data set with a SSHA score of 150, where would she fall in the distribution? Give a good justification of how she compares to the other women in the study.

11. Study for QUIZ Tomorrow!
Homework
Study for QUIZ Tomorrow!