Precision
The closeness of repeated measurements of the same quantity to one another, regardless of their accuracy.
Formula / equation
RSD = (s / x̄) × 100
Unit
Dimensionless
In depth
Precision reflects random error and is quantified as standard deviation, relative standard deviation or range. Repeating a measurement improves the precision of the mean as the square root of the number of trials. A method can be highly precise yet badly inaccurate if a systematic bias is present.
Examples in the real world
Titre volumes of 24.55, 24.57 and 24.56 mL are highly precise; values of 23.1, 25.8 and 24.4 mL are not.