Statements on conformity in test reports / decision rule

At the request of our customers, statements on the conformity of the results can be commissioned in test reports. The statements on conformity can be made, for example, by statements such as passed / failed or within / outside the tolerance limits or within the framework of a rating system.

For this purpose, the specifications or standards must be clearly specified by our customers. If these are not included in the requested specifications or standards, the applied decision rule will be stated by PiCA Prüfinstitut Chemische Analytik GmbH in the test report and transmitted to our customers.

PiCA Prüfinstitut Chemische Analytik GmbH reserves the right to refuse statements on the conformity of results if it does not have the necessary competences or has not been sufficiently informed by our customers about the facts of the case and, if applicable, the associated legal basis.

Knowledge of the uncertainty associated with measurement results is essential for the interpretation of results. Without information about the uncertainty of analytical results, there is a risk of misinterpretation.

For the evaluation of conformity based on quantitative results, different scenarios can be considered, which can be illustrated in 4 case studies.

A distinction must be made between:
CASE 1: Clear excess
CASE 2: Non-unique overrun
CASE 3: Inconclusive underrun
CASE 4: Clear underrun

Cases 1 and 4 are unambiguous, since the decision is not influenced by the measurement uncertainty. The measurement uncertainty characterizes a range of values which contains the true value of the measurand, taking into account random and systematic errors with a high statistical probability.

In cases 2 and 3, however, considerations for the definition of objective criteria (decision rules) are necessary, since the measurement uncertainty interval overlaps with the limit value. Non-conformity cannot automatically be inferred from an ambiguous exceedance (see case 2). However, for each ambiguous exceedance or ambiguous undercut (see case 3), a notice to the respective client is necessary, since the measurement result violates the specified value.