I’ve seen it time and time again: the glazed-over look that comes across someone’s face when the topic turns to anything vaguely sounding like statistics. Admittedly, it’s a rare sort of person who gets excited about sigmas and rhos but anyone who is involved in standardized testing needs to have at least a hand-shaking relationship with reproducibility and repeatability. Repeatability and reproducibility are the core components of precision.

It is actually pretty simple, the terms already tell you what they mean. Repeatability is the variability associated with test results obtained from one operator, one measurement device when performed repeatedly. Reproducibility is the variability of the measurement system due to different operators, different measurement devices or test conditions; essentially how closely the test result can be reproduced. High repeatability + high reproducibility = greater precision.