The laboratory uses established decision rules to determine the conformity of a result with a
specification / statutory limit / contractual limit.

In the absence of such rules, the laboratory applies the following decision rule, unless the
customer specifies their own rules regarding their specifications.

Case A: The result of a test X complies with a specification / statutory limit / contractual limit L
(L₁ = upper limit, L₂ = lower limit), when the result, including the uncertainty limits ±U for a 95%
confidence interval, falls within the specification / statutory limit / contractual limit:
X + U < L₁ or X - U > L₂

Case D: The result of a test X does not comply with a specification / statutory limit / contractual
limit L (L₁ = upper limit, L₂ = lower limit), when the result, including the uncertainty limits of the
result ±U for a 95% confidence interval, falls outside the specification / statutory limit /
contractual limit:
X - U > L₁ or X + U < L₂

NOTE:
In cases where the test result is within or outside a specification / statutory limit /
contractual limit, but its distance from the specification limit is less than the uncertainty limits of
the result for a 95% confidence interval (Cases B and C), the laboratory does not make a
statement of conformity or non-conformity.

The four compliance cases A, B, C, and D are illustrated in the diagram below: