11.1 Types of data and displays

​Types of Data


Categorical data (qualitative) consists of labels or nonnumerical data that can be separated into categories. Examples: Hair color, Grade level, Postal Code

Numerical data (quantitative) consists of numbers that represent counts and measurements. Examples: Height, Shoe size, Hours, Number of ...

Univariate data measures one characteristic of a population.

Bivariate data measures two characteristics of a population.

Mr. Dohnal takes a survey of all of his Algebra 1 students
(7th and 8th graders). In the survey he asks each student " What is your favorite color ?"

This is an example of bivariate categorical data.
The 2 things being measured are grade level and favorite color. Both measurements are categories (nonnumerical).

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​Example: Identifying the type of data

Multiple Choice

CLASSIFYING DATA

Tell whether the data are categorical or numerical, and univariate or bivariate:

ages of students in a school

• Numerical, univariate

• Categorical, univariate

• Numerical, bivariate

• Categorical, bivariate

Multiple Choice

CLASSIFYING DATA

Tell whether the data are categorical or numerical, and univariate or bivariate:

last names and favorite colors of students in your class

• Numerical, univariate

• Categorical, univariate

• Numerical, bivariate

• Categorical, bivariate

Multiple Choice

CLASSIFYING DATA

Tell whether the data are categorical or numerical, and univariate or bivariate:

prices and ages of homes in a neighborhood

• Numerical, univariate

• Categorical, univariate

• Numerical, bivariate

• Categorical, bivariate

Multiple Choice

CLASSIFYING DATA

Tell whether the data are categorical or numerical, and univariate or bivariate:

types of songs played at a jazz concert (swing, blues, …)

• Numerical, univariate

• Categorical, univariate

• Numerical, bivariate

• Categorical, bivariate

Data Displays

The next slides will discuss the strengths and some weaknesses of the 9 different data displays. Pay attention to what type of data it represents (numerical, categorical, univariate, bivariate).

A type of chart that uses segmented bars that add up to 100% to help us visualize the distribution of bivariate categorical data.

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Segmented bar graph

Practice Questions
Reading and Interpreting different data displays

Multiple Choice

How many students have 0 Brothers and Sisters? 

• 6 students
• 0 students
• 12 students
• 10 students

Multiple Choice

How many students were greater than 55 inches tall but less than 70 inches tall?

• 13
• 15
• 16
• 17

Multiple Choice

What is the highest quiz grade in the stem and leaf plot?

• 9
• 26
• 92
• 96

Multiple Choice

Why would you use a circle graph?

• when you have continuous data

• to compare the frequency of the data

• when the data is too large for any other graph

• to show how the total data is divided into parts

Multiple Choice

Which scatterplot does NOT suggest a linear relationship between x and y?

Multiple Choice

Which statement is true based on the segmented bar graph above?

• The number of kids with cell phones is about the same for ages 13-15 and 16-18

• About 75% of kids with cell phones are ages 13-15

• About 75% of kids age 13-15 have a cell phone

• 320 kids were involved in this survey

Multiple Choice

According to this pie graph, what is the most popular flavor of Jolly Rancher?

• Blue Raspberry

• Grape

• Green Apple

• Watermelon