Measurement & Experimental Science
Uncertainty, Repeatability & Reproducibility
Repeated measurements naturally vary. Understanding repeatability, operator differences, instrument differences, sampling variation, and environmental variability prevents small numerical differences from being overinterpreted.
Key concepts
- Repeatability describes variation under similar measurement conditions
- Reproducibility includes changes such as operator, day, or instrument
- Biological variability and instrument uncertainty both contribute
- A difference smaller than normal variation may not be meaningful
What to measure or observe
- Take replicate measurements on the same sample when appropriate
- Compare operators or meters periodically
- Track standard deviation or range
- Report method and sample count with the result
Common mistakes
- Reporting one measurement without context
- Treating the last decimal place as biologically meaningful
- Averaging away outliers without investigating them
- Comparing methods with different uncertainty as if identical
Visuals this lesson still needs
- Repeatability versus reproducibility
- Sources-of-uncertainty diagram
- Overlapping measurement distributions
- Method-reporting checklist