Precision and Accuracy
Etymology
“Precision” is from Latin “praecisio” (a cutting off), from praecidere (to cut short); “accuracy” from “accuratus” (done with care), from ad plus cura (care). The two words drifted together in everyday use but stayed distinct in science.
noun phrase · /prih-SIZH-uhn and AK-yer-uh-see/
Two different virtues of a measurement: accuracy is closeness to the truth, precision is consistency between repeated readings.
What it names
It untangles a distinction people collapse daily — being repeatably wrong is not the same as being right.
Example
A scale that reads 5.02, 5.01, 5.03 kilograms for a true 4-kilogram weight is precise but not accurate — consistent, and consistently wrong.
Related idea
A confident, tightly clustered set of figures can be badly biased away from the truth; high precision with low accuracy is exactly how a broken instrument, or a well-run but biased poll, fools people — related to the margin of error, which measures precision, not accuracy.