Question 1

What is proficiency testing (PT)?

Accepted Answer

Proficiency testing is an external quality assessment in which a laboratory analyzes the same test material as many other laboratories and compares its results against an assigned reference value, to demonstrate the reliability of its measurements.

Question 2

What is a PT scheme?

Accepted Answer

A PT scheme is an ongoing proficiency-testing program for a defined field, such as water chemistry, organized into repeated rounds over time.

Question 3

What is a round?

Accepted Answer

A round is a single testing cycle within a scheme, with its own sample distribution, data-entry window and statistical evaluation.

Question 4

What is a z-score?

Accepted Answer

A z-score expresses how far a laboratory result deviates from the assigned value in units of the standard deviation for proficiency assessment. A result with an absolute z-score of 2 or less is generally considered satisfactory, while 3 or more is considered unsatisfactory.

Question 5

What is a measurand?

Accepted Answer

A measurand is the specific quantity being measured, such as the concentration of a particular analyte like lead or pH in the test sample.

Question 6

How do I participate in a proficiency testing round?

Accepted Answer

A laboratory registers for a scheme, receives the test samples for each round, analyzes them like routine samples, submits its results before the deadline and then receives an evaluation report.

Question 7

What do I receive after a round?

Accepted Answer

Participants receive a report containing the assigned value, their own result, the z-score and further performance statistics for each measurand.

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Products overview for Proficiency tests