Displaying
Categorical Data
CH. 3 Day 1 Notes
AP Statistics
EQ: How do we display categorical data?
Warm Up
Identify the W’s, name the variables and
specify if it should be treated as categorical
or quantitative.
A listing posted by the Arby’s restaurant
chain gives, for each of the sandwiches it
sells, the type of meat in the sandwich, the
number of calories, and the serving size in
ounces. The data might be used to assess
the nutritional value of the different
sandwiches.
Warm Up - Answer
• Who (are we studying): Arby’s sandwiches
• What (characteristics are we using):
o Type of meat (categorical)
o number of calories (quantitative)
(calories)
o serving size (quantitative) (ounces)
• When: Not specified
• Where: Arby’s restaurants
• How: We are using the list posted by the
restaurant
Tell whether the variable is categorical,
quantitative, or an identifier.
1.Shoe size
2.VIN number of a car
3.Number of pages in a book
4.Class rank
5.Length of your arm
Extra
In what way might Age be
considered to be a
quantitative variable?
What about as a categorical
variable?
Ways to Represent Data
Today we will focus on:
Frequency Tables
Bar
BarCharts
Charts
Relative
Frequency Tables
Pie Charts
Frequency Tables
• Helps organize data
• Records totals and categories
• Relative frequency table-displays
the percentages(proportions) of
the values in each category.
Make a frequency table and a relative frequency table
of the following averages for previous AP Stats students.
A
F
C
F
C
B
B
C
A
D
B
C
D
D
B
B
D
C
B
A
C
A
A
B
B
C
C
D
D
F
F
Why make a picture?
• It may reveal things you can’t see in
the table
• It shows important features
• It helps you tell about the data to
others
Things to Remember…
•
•
•
•
Context
Appropriate Scale
Area Principle
Label!
oInclude units where
applicable
Make a bar chart of the previous
AP Stats averages by letter grade.
You may also see it like
this…
F
D
C
B
A
0
1
2
3
4
5
6
7
What do we see in the
graph?
Make a relative frequency bar chart of the
previous AP Stats averages.
Pie Charts
Make a pie chart of the
previous AP Stats averages.
A
B
C
D
F
A
B
C
D
F
What do we see in the
graph?
•
•
•
•
A should look bigger than F
B and C should look the same
B and C should look twice the size of A
D should appear larger than A
• Can approximate areas
• Can also use Geometry to calculate Central Angle
measures (cross-curricular)
Important Disclaimer:
CAN ONLY USE BAR
CHARTS AND PIE CHARTS
AS LONGS AS INDIVIDUALS
BEING STUDIED
DO NOT FALL INTO MORE
THAN ONE CATEGORY.
The table below gives the distribution by region of
the population in the United States in 1996.
Region
Population(in millions)
Northeast
51.6
Midwest
62.1
South
93.1
West
58.5
Make a pie chart of the
population data.
NE
MW
S
W
Homework
p. 36-44 # 5, 7, 8, 10, 11, 13, 14
(due Monday)
Reminder:
Due tomorrow1) p.16 Homework from Textbook
2) Reading Questions Ch.2-3