A budget mistake in which one effect appears in two rows, such as listing a meter's drift on its own line when the manufacturer's one-year spec already in the budget includes drift, or entering a standard's short-term noise once from its certificate and again from your own repeat readings. It overstates uncertainty, which shrinks claimed capability, fails good product and pushes labs toward needlessly expensive equipment. Reviewers hunt for it alongside its opposite, a missing contributor.
You've got the meter's 1-year spec and its drift as separate lines, that's double counting, the spec already covers drift.
Also heard as
- double dipping
Related terms
Uncertainty budget
A table listing every uncertainty source in a measurement with its size, distribution, divisor and contribution to the total.
Spec
Shop clipping for a manufacturer's accuracy specification, the published limits an instrument should stay within.
Drift
Gradual change in an instrument's readings over time that comes from the instrument itself, not from what it measures.
Repeatability
How tightly readings bunch when one person repeats a measurement with the same setup, in one place, in one short sitting.