Use when
- Baseline-to-follow-up change is more informative than a single terminal comparison.
- The endpoint can be measured repeatedly with acceptable carryover risk.
- The analysis plan accounts for within-subject correlation.
Study Designs
Study design
Repeated-measures designs
Repeated-measures designs collect endpoints from the same subject across time or conditions.
Decision summary
Use repeated measures when within-subject change is the scientific question and repeated exposure will not train, sensitize, fatigue, or stress the animal enough to dominate the endpoint.
| Design unit | Same subject measured across time, dose, condition, or phase. |
|---|---|
| Benefit | Can reduce between-subject variability and clarify trajectories. |
| Risk | Learning, habituation, sensitization, fatigue, or order effects. |
| Reporting | State timing, order, washout, and analysis model. |
Do not use when
- The method is destructive, strongly learned, terminal, or highly sensitive to prior exposure.
- Carryover cannot be controlled or measured.
Caveats
- Repeated testing can change behavior, especially in learning and stress-sensitive methods.
- Missing observations are not interchangeable with independent-group missingness.
- Baseline normalization can hide group differences if not planned carefully.
Reporting checklist
- Report sequence and timing.
- State whether order was counterbalanced.
- Define washout or rest periods.
- Report handling of missing observations.
- Use an analysis method appropriate for repeated observations.
References
Percie du Sert et al. 2020. The ARRIVE guidelines 2.0.
Reporting expectations for design and analysis transparency.
https://pubmed.ncbi.nlm.nih.gov/32663219/
Festing and Altman 2002. Guidelines for the design and statistical analysis of experiments using laboratory animals.
Animal-study design and statistical analysis guidance.
https://pubmed.ncbi.nlm.nih.gov/12100861/
Related surfaces
Use these related surfaces to move from the scientific method question to the relevant product page, endpoint definition, analysis tool, or adjacent guide.
