Two Categorical Variables

We've already looked at how we can use a table to display data we collect. Normally this is based on one group who may answer in a certain number of ways. For example, you could ask everyone in your class to choose their favourite type of juice and display your results in a graph or table, such as the one below.

Type of Juice	Number of People
Apple	$12$12
Pineapple	$4$4
Orange	$8$8
Tropical	$5$5

 

But what would we do if we wanted to know whether there were differences in juice preferences between boys and girls? Well, we would need to create a two-way table. Let's learn how to do this.

Let's recap the video:

To create a two-way table, we list the different groups along one side of the table and the different categories on the other, like so:

Type of Juice	Boys	Girls
Apple	$5$5	$7$7
Pineapple	$3$3	$1$1
Orange	$6$6	$2$2
Tropical	$2$2	$3$3

Notice how the two groups, boy and girls, are the headings for the columns and each variable (i.e. each type of juice) is a separate heading for each row? Now we get even more information! For example, I can say apple juice was preferred by most girls ($7$7 girls picked it), while most boys preferred orange juice ($6$6 picked it). Or I could say $2$2 more boys preferred pineapple juice than girls (because $3-1=2$3−1=2).

We can also display our results in a graph, with the two groups side-by-side, like in the column graph below:

 

Worked Examples

Question 1

 

Question 2