Processprecision

Processprecision, sometimes written as “process precision,” is a concept used in quality engineering to describe the degree to which a process produces consistent, repeatable results under unchanged conditions. It focuses on repeatability and the closeness of agreement among repeated measurements or outcomes of the process. Precision is distinct from accuracy: a process can be highly precise (low variability) but biased (off Target), and conversely a process can be accurate on average but imprecise (high variability).

Measurement of process precision commonly relies on statistical metrics that quantify variability. The standard deviation, variance, or coefficient of variation of repeated measurements provides a numeric sense of precision. In manufacturing and analytics, control charts (such as individuals and moving range charts) monitor ongoing precision over time, helping detect increased dispersion or instability in the process.

Relation to process capability is important. A highly precise process may still fail to meet specifications if it is not centered near the target, producing a biased mean. Capability indices like Cp and Cpk assess both spread (precision) and centering (accuracy) relative to specification limits.

Strategies to improve process precision include reducing sources of variation, calibrating instruments regularly, performing measurement system analysis to separate measurement error from process variation, stabilizing the environment, and applying structured optimization methods such as design of experiments or Six Sigma. Clear documentation of procedures and ongoing monitoring are essential to maintain and verify precision over time. See also accuracy, variation, measurement system analysis, and statistical process control.