Which of the following is an example of a categorical variable?

• A. Temperature
• B. Material type
• C. Mass
• D. Time

Answer: (B)

Categorical variables are qualitative data that group observations into distinct categories without a meaningful order or numerical value. Material type fits this because you classify items as metal, plastic, wood, and so on. These categories are names, not numbers, and you can count how many items fall into each category but you don’t perform arithmetic like averaging on the category itself.

In contrast, the other options are numerical (quantitative) variables. Temperature, mass, and time are measured with numbers and can be ordered, added, or averaged (for example, averaging temperatures or total mass).