Let's begin by recalling that we use two-way frequency tables to display and interpret relationships between paired categorical data. In categorical data, each data point falls into one of the categories. Let's consider an example.

	Ebooks or Audiobooks?
Gender	Ebook	Audiobook	Total
Male	$22$	$26$	$48$
Female	$27$	$25$	$52$
Total	$49$	$51$	$100$

This two-way frequency table describes the relationship between type of digital copy of a book and gender. There are

2

categories for the types of digital copies of books and

2

categories for gender. Each cell of the table tells us about the frequency of one combination of categories.

This means that a two-way frequency table shows all possible combinations of categories together with their frequency. That is how it presents the relationship between sets of paired categorical data.

Extra

The Difference Between Categorical and Measurement Data

As we noted earlier, two-way frequency tables are used to show the relationship between paired categorical data. The other type of data is called the measurement data. Let's compare these two data types.

	Measurement Data	Categorical Data
Definition	Consists of data that are measures — can be expressed as numbers.	Consists of data that belongs to one or more categories.
Method of Displaying	Scatter plot	Two-way frequency table
Example	Age	Colors

Exercise