Variable
A variable is a characteristic that can change from one observational unit to another, and it is what you record about each individual.
The observational unit is what you measured; the variable is what you recorded about it, and it earns the name variable because its value changes from one unit to the next. Variables come in two types: categorical ones take category names or group labels, and quantitative ones take numerical values for a measured or counted quantity, usually with units. For example, across 30 students, grade level is categorical while commute time in minutes is quantitative, so a mean commute of 14.5 minutes is meaningful and a mean grade level is not. A numerical summary of a variable is a parameter for a population and a statistic for a sample.
Where this comes up
- Confounding vs lurking variable: how they differComparison
- Categorical vs quantitative variables (with examples)Guide
- Discrete vs continuous variables explainedComparison
- AP Stats 1.2: VariablesAP topic
- Discrete random variable practice problemsPractice
- AP Stats 2.8: Random Variables & DistributionsAP topic
- AP Stats 2.9: Mean & SD of Random VariablesAP topic
- Expected value and random variable practice problemsPractice
82 pages on the site use this term.
More variables and data types terms, or browse the full statistics glossary.