Precision

Definition

The degree of reproducibility or consistency of repeated measurements, estimates, or observations under unchanged conditions; distinct from accuracy, which describes closeness to a true value. In biological research, precision reflects the reliability of quantitative data and the robustness of sampling or analytical methods.

Etymology

From Latin praecisio, meaning 'a cutting off,' via Old French precision; in scientific usage since the 18th century to denote exactness in measurement.

Example

A pitfall-trap survey of ground beetle (Carabidae) assemblages achieves high precision when replicate traps at the same site yield similar abundance estimates across sampling periods, even if the absolute counts deviate from the true population size due to trap avoidance behavior.

Synonyms

• repeatability
• reproducibility

Related Terms

• Accuracy
• Bias
• error
• standard deviation
• confidence interval
• sampling effort
• measurement uncertainty

Usage Notes

Precision and accuracy are often conflated but are orthogonal: precise measurements cluster tightly (low variance) but may be systematically biased; accurate measurements center on the true value but may be imprecise (high scatter). In entomology, precision is typically quantified by coefficient of variation, standard error, or repeatability statistics; improving precision often involves increasing sample size, standardizing protocols, or using more sensitive instruments. Precision applies to continuous measurements (e.g., body length), count data (e.g., trap catches), and estimates derived from models (e.g., population density from mark–recapture).