Percent error vs percent difference
The formulas use different denominators and answer different questions, so always name the reference and equation.
Percent error needs a reference
Use the absolute observed-minus-reference difference divided by the absolute reference, multiplied by 100%. A zero reference makes the percentage undefined.
Percent difference treats values as peers
A common symmetric form divides the absolute difference by the mean magnitude of the two values. Neither measurement is declared authoritative.
State the denominator
Do not report only a percentage. Name the formula, values, units, and reference so a reader can reproduce the result and understand what it compares.
Do not turn a percentage into proof
A small percentage does not establish accuracy or validity; the reference quality, uncertainty, and experimental design remain relevant.
Sources and boundaries
Solice develops LabCrux. The independent sources above do not sponsor or endorse the product. This page explains a review method; your experimental evidence, course instructions, and instructor remain authoritative.