4.1 Tables and Graphs for the Relationship Between TwoVariablesObjectives:By the end of this section, I will beable to…

1) Construct and interpret crosstabulations for two categorical variables.

2) Construct and interpret clustered bar graphs for two categorical variables.

3) Construct and interpret scatterplots for two quantitative variables.

Section 4.1Tables and Graphs for

TWO Variables.

Crosstabulation

• Fancy word for a table. It is also known as a two-way table

• Helps you look for patterns in a data set.

Two-way Table

• Make a two way table to help you organize information.

Who? Who? TOTAL

What?

What?

TOTAL

Question: Do you eat breakfast regularly?

Two-way Table

Male Female TOTAL

Eats Breakfast Regularly

Doesn’t Eat Breakfast RegularlyTOTAL

Question: Do you eat breakfast regularly?

Graphs for Crosstabulations

When to use?

• Crosstabulations and clustered bar graphs are useful for summarizing the relationship between CATEGORICAL variables.

What happens if you have QUANTITATIVE data?

• Use a SCATTERPLOT

SCATTER PLOTS• graphs that display a relationship

between two variables

VARIABLES

What are the two variables?

What are the two variables?

Three Types of Scatterplot Relationships

• Positive• Negative• No relationship

ASSOCIATIONPositive Relationship:

Larger values of one variable tend to be associated with larger values of the other variable.

Negative Relationship:Larger values of one

variable tend to be associated with smaller values of the other variable.

NO RELATIONSHIP

EXAMPLES

Question?

• Is there a relationship between how many digits you can type into your calculator and how fast you can do it?

Total Digits Typed

Tim

e (i

n s

eco

nd

s)

x axis

y ax

is