Chapter 3 Displaying and Describing Categorical Data AP Statistics

Categorical vs Quantitative Data

Categorical data:

Names categories and answers questions about how cases fall into those categories. Can be a number, example: grade in school (12 th )

Quantitative data:

Answers questions about the quantity of what is measured. Takes numerical values for which things like averages make sense.

Displaying Categorical Data • Tables (frequency tables) • Bar chart • Pie chart • Segmented Bar Graph – Good for comparing, looking for independence.

– Only use for percents—not counts

Displaying Categorical Data Area Principle Basically—don’t make graphs 3-D. May look nice, but is not accurate.

Describing Categorical Data

Smoker 32 Non Smoker 61 Total 93

High school 2 yr college 4+ yr college Total

5 13 50 17 72 150 22 85 200

Describing Categorical Data Create a segmented bar graph comparing education level among smokers and non smokers.

High school 2 yr college 4+ yr college Total

Smoker 32 5 13 50 Non Smoker 61 17 72 150 Total 93 22 85 200

Describing Categorical Data Do you think smoking is independent of education level?

High school 2 yr college 4+ yr college Total

Smoker 32 5 13 50 Non Smoker 61 17 72 150 Total 93 22 85 200