Categorical variable: data represent groups Examples: rankings, binary outcomes Formal definition: Names or labels (i.e., categories) with no logical order or with a logical order but inconsistent differences between groups (e.g., rankings), also known as qualitative.

Quantitative variable: data represent amounts Examples: height, weight, or age Formal definition: Numerical values with magnitudes that can be placed in a meaningful order with consistent intervals, also known as numerical.