Inside GMP 11: setting calibration intervals you can defend

'Calibrate annually' is a habit, not an analysis. NIST's GMP 11 — in the library — is the short, blunt antidote: intervals should come from the behavior of the standard, not the calendar's convenience.

The document walks the factors that legitimately set an interval: the stability history of the artifact or instrument, how hard and how often it is used, the environment it lives in, the tolerance it must hold, and the cost of being wrong. It pairs naturally with the control-chart procedures: a check standard in statistical control is continuous evidence that the interval is not yet exhausted; an out-of-control point is evidence that it was too long.

ILAC-G24 supplies the formal adjustment methods when you have as-found data in volume. The interval-analysis calculator in our Tools section implements the simplified reliability-target model from that family — useful for a first pass, with GMP 11's caveats attached.