Proficiency Testing Record

This record is the external check on results already being produced routinely. Using it to record ordinary sample results, or to document why a method was accepted in the first place, produces a register nobody can query for either purpose.

ISO 17025 cl.7.7 requires laboratories to monitor the validity of their results, and participation in proficiency testing or interlaboratory comparison is the principal external mechanism for doing so.

ISO 17025 is applied through national accreditation bodies, and in food testing, through regulation that ties a laboratory's standing to demonstrated ongoing proficiency. What counts as an adequate response to a poor round differs by who is asking.

Filling in every field is mechanical. The judgement is in how far a poor round's consequences are traced back into routine work.

These are the gaps an assessor, or an internal audit, finds most often in proficiency testing records.

A sodium result came back Questionable, comfortably inside the scheme's tolerance for an overall Satisfactory round, and the laboratory closed it with Investigation Opened marked Not required. Two rounds later the same parameter came back Unsatisfactory, and only then did anyone check whether the first round was a warning.

Tracing it back, a conductivity probe had begun drifting before the first round and was still in routine use for every batch tested in between. Treating the earlier Questionable rating as the trigger it was, rather than as a pass because the overall round looked fine, would have caught the drift two rounds and an unknown number of routine results earlier.

The form only proves one round was entered and rated. Chasing every questionable result into an actual cause, and every cause into whatever it should trigger, is the ongoing work.

KnowQuality

Holds the proficiency testing register against the scheme calendar, and flags a questionable or unsatisfactory rating that never got its investigation opened.

KnowMaintain

Tracks the calibration and service history of equipment implicated when a proficiency test cause is traced back to drift, so the connection between the two records is not lost.

KnowTrain

Holds the training and competence record behind Analyst Retraining Required, so a proficiency test finding actually closes out against a completed retraining, not just a ticked box.

Ella

Coordinates the crew across proficiency testing, method verification and calibration, and holds every write for your approval before it touches a record.

Assigned value

The reference value set by the proficiency testing provider for a round, usually derived from a formulation, a reference method, or the consensus of participating laboratories.

z-score

A standardised measure of how far a laboratory's result sits from the assigned value, expressed in units of the scheme's target standard deviation, letting different parameters be judged on a common scale.

Ring trial / proficiency scheme

An organised programme in which the same sample, or matched samples, are distributed to multiple laboratories for independent testing, so each laboratory's performance can be compared against the group.

Satisfactory / questionable / unsatisfactory rating

The scheme's own classification of a result's z-score or equivalent statistic, distinct from whether the result would have passed the laboratory's internal specification for the same parameter.

Routine method and routine analyst

The method version and the analyst or analyst pool the laboratory actually uses for real samples, as opposed to a specially prepared method run or a senior analyst brought in only for the scheme sample.