Clause 7.7: Ensuring the validity of results

What the clause asks for

Clause 7.7 requires a procedure for monitoring the validity of results, with data recorded so that trends are detectable and, where practicable, statistical techniques applied to review them. The monitoring is planned and reviewed.

Clause 7.7.1 lists internal means of monitoring, as appropriate: use of reference materials or quality control materials, alternative instrumentation, functional checks, check or working standards with control charts, intermediate checks, replicate tests or calibrations, retesting of retained items, correlation of results for different characteristics, review of reported results, and intralaboratory comparisons.

Clause 7.7.2 requires monitoring by comparison with other laboratories where available and appropriate: participation in proficiency testing (PT) or in interlaboratory comparisons other than PT.

Clause 7.7.3 requires the data from these activities to be analysed and used to control and, if applicable, improve the laboratory’s activities. Results outside predefined criteria lead to action to prevent incorrect results being reported.

What assessors sample

Assessors ask for the PT plan covering the scope of accreditation, the most recent reports, and what happened after any questionable or unsatisfactory result. Most accreditation bodies set a minimum PT frequency per technical area in their own policy. Common findings:

• A PT plan that leaves part of the scope uncovered for the accreditation cycle.
• Unsatisfactory z-scores with no investigation or nonconformity raised.
• Control charts kept but never reviewed against action limits.

Where this lives in AccreditBook

Requirement	Where it is recorded
PT plan (7.7.2)	Proficiency testing: scheme, provider, scope area, required frequency in months, planned date
PT rounds and status	Status from planned through enrolled, in progress, submitted to evaluated
PT results	Per analyte or measurand: reported value, assigned value, z-score, En number, outcome
Action on outliers (7.7.3)	“Raise NCR” from an unsatisfactory result, linked both ways
Internal monitoring (7.7.1)	Intermediate checks as calibration events; records of reviews attached as evidence

The proficiency testing plan groups rounds by scope area and shows when each area was last covered and when it is next due, so a gap in coverage appears on the dashboard before the assessor finds it.

See Proficiency testing and Nonconformities.