Chapter 2: Describing and Displaying Categorical Data

Question 1

How To Spot A Misleading Graph

Answer 1

1. It may not have axis labels or scale. It may cut off the x or y axis, or start at a weird place
2. It may use pictures for bar graphs

Question 2

How To Make Bar Charts For Categorical Data

Answer 2

1. Label axes: variable name on horizontal axis; frequency/relative frequency on the vertical axis
2. Scale axes: category labels spread out along x-axis; start scaling vertical axis at 0 an go up in equal increments until you equal or exceed the maximum frequency/relative frequency
3. Draw bars: make the bars equal in width and leave gaps between them. The heights of the bars represent the category frequencies or relative frequencies

Question 3

How To Make Pie Charts For Categorical Data

Answer 3

1. Make sure percentages add up to 100%
2. Include a legend/key that connects categories to pie pieces

Question 4

Segmented Bar Graph

Answer 4

Stacks up bars to make 100%

Question 5

Mosaic Plot

Answer 5

Segmented bar graph where the width of bars is proportional to the group size

Question 6

Association

Answer 6

If knowing the value of one variable helps us predict the other variable - segmented bar graphs are different (no association=independent)