Part I: Exploring and Understanding Data

Chapter 2: Displaying and Describing Categorical Datapages 14 - 22

  1. Frequency Tables record totals and category names
  2. Table 2.2 pg. 16 where the categories are ticket class on the Titanic using ______
  3. Table 2.3 pg. 16 where the categories are ticket class on the Titanic using ______
  1. Bar Charts display the distribution of a categorical variable, showing counts of each category next to each other for easy comparison like in Figure 2.3 pg.17
  2. They should have small spaces between the bars to indicate these are free standing bars that could be ______in any order
  3. If we wanted to draw attention to the relative proportion falling into each class, then we could use a ______bar chart like Figure 2.4 pg. 17
  1. Pie Charts
  2. These show how a whole group breaks into several categories
  3. They slice the circle into pieces whose sizes are ______to the fraction of the whole in each category as in Figure 2.5 pg. 18
  1. Contingency Tables pages 18 - 20
  2. These tables shows how the individuals are distributed along each variable contingent upon the value of the other variable
  3. Examples pages 18 – 19: Class and Survival

Class
First / Second / Third / Crew / Total
Alive / 203 / 118 / 178 / 212
Survival / Dead / 122 / 167 / 528 / 673
Total
  1. Each cellgives the count for a ______of values of the two variables
  2. The margins, both on the right and at the bottom, give ______
  3. Complete the marginal distribution for class (bottom line)
  4. and the marginal distribution for survival (right column)
  1. To compare these numbers, let’snow calculate the table percentages

Class
First / Second / Third / Crew / Total
Alive
Survival / Dead
Total / 100%
  1. Conditional Distributions: these show the distribution of one variable for just those cases that satisfy a condition on another variable
  2. The conditional distribution of ticket class conditioned upon survival in Table 2.7 on page 20
  3. The conditional distribution of survival for each category of ticket class in Table 2.8 on page 21
  4. Make some observations from these tables: ______

______

  1. Study the bar charts on pg. 22.
  2. Do you think the risk was about the same across all ticket classes? Justify your response!
  1. If the risk was about the same across all ticket classes, we would say that survival is independent of class. Are the variables class and survival independent? Why or why not?
  1. We will frequently explore the concept of independence and will eventually learn ways to check for independence formally.
  1. Classwork: Complete “Just Checking” on page 24

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VII. Homework #’s 5 – 15 pages 34 – 36