Experimental unit
An experimental unit is the individual or object a treatment is assigned to; when the units are people they are called subjects or participants.
The experimental unit is whatever gets randomly assigned, and naming it correctly sets how many units the study really has. For example, if a teacher assigns one review method to each of 6 whole classes, the experimental units are the 6 classes, not the 150 students inside them. Calling the students the units would inflate how much evidence you think you have. Keep it separate from the observational unit, which is whatever a measurement gets recorded on: here the experimental unit is the class, while the response is recorded for each of the 150 students.
Where this comes up
- How to describe a completely randomized designGuide
- How to design an experiment and describe itGuide
- Experimental design practice problems (8)Practice
- Experiment vs observational study: what to concludeGuide
- Scope of inference practice problems (8 solved)Practice
- AP Stats 1.10: Data CollectionAP topic
- AP Stats 1.13: Experimental DesignAP topic
More collecting data and study design terms, or browse the full statistics glossary.