The first set of classes has different widths, some 5.9 and some 4.9.

The second set of classes has gaps. Notice that the value of 21.3 doesn't fit into any class.

The third data set doesn't start low enough. The value 2.8 doesn't fit.

On the other hand, qualitative data, also called categorical data, are usually not numeric. There are categories to choose from, such as gender (male, female), type of vehicle (car, truck, SUV), and pet ownership (have a pet, do not have a pet).

A Venn diagram displays categorical data. Here, people were surveyed and asked whether they played the piano and whether they had a pet.

To construct a two-way table:

Think About It: The number of choices for the categories of either variable can be more than two.

Describe how to create a two-way table from a Venn diagram that has two intersecting loops.

How can you check that you created a two-way table correctly?

It is tough to get an exact figure because some shelters don’t keep records, often because they don’t have the time or staffing to do so. Shelters that do keep records often find that it is well worth the time and cost of doing so. For example, they can use the data to back up claims about their current needs, which encourages supporters to donate the types of supplies that will help the shelters the most. They may also report numbers to the media about how many animals were adopted, sent to animal sanctuaries, or sent to foster care homes over a given period of time. More positive media attention yields more donors and volunteers.