Understanding conformity assessments: standards, terminology and relationships

At first glance, the meanings of terms such as testing, inspection, certification or accreditation may seem apparent from everyday language. A closer look soon reveals, however, that these terms are used inconsistently in everyday contexts. Clear definitions based on standards are therefore essential for technically sound use.

Such a foundation is provided by the DIN EN ISO 9000 series (quality management) and the DIN EN ISO/IEC 17000 series (conformity assessment). The following are particularly relevant:

• DIN EN ISO 9000: Quality management systems – Fundamentals and vocabulary.
• DIN EN ISO/IEC 17000: Conformity assessment – Vocabulary and general principles.
• DIN EN ISO/IEC 17050: Conformity assessment – Supplier’s declaration of conformity.
• DIN EN ISO/IEC 17025: Requirements for the competence of testing and calibration laboratories.
• DIN EN ISO/IEC 17020: Requirements for inspection bodies.
• DIN EN 45011: Requirements for bodies operating product certification systems.

Below, we explain key terms and their relationships. This also illustrates how closely they are linked to aspects such as competence, confidence, impartiality and independence.

Basic terms according to DIN EN ISO 9000

DIN EN ISO 9000 defines key quality management terms:

• Conformity: fulfilment of a requirement.
• Verification: confirmation that specified requirements have been fulfilled.
• Validation: confirmation that requirements for a specific intended use have been fulfilled.
• Nonconformity: non-fulfilment of a specified requirement.
• Defect: non-fulfilment of a requirement relating to an intended or specified use.

Key conformity assessment terms according to DIN EN ISO/IEC 17000

DIN EN ISO/IEC 17000 extends these fundamentals with specific definitions:

• Conformity assessment: demonstration that products, processes, systems, persons or bodies fulfil specified requirements.
• Conformity assessment body: a body that performs conformity assessments.

The standard distinguishes between the following types of conformity assessment body:

• First party: assessment by a body that itself manufactures or supplies the object of conformity assessment (for example, a manufacturer, supplier or provider),
• Second party: assessment by an interested party with an interest in the object of conformity assessment (for example, a customer or user),
• Third party: assessment by an external body independent of the object of conformity assessment and of its manufacture or use.

Other key terms:

• Sampling: taking a sample according to a specified procedure
• Procedure: a specified way of carrying out a process
• Methods for determining conformity

Methods for determining conformity

Let us look more closely at the last point. DIN EN ISO/IEC 17000 describes various methods for establishing conformity.

• Testing: determination of characteristics of an object of conformity assessment using defined procedures.
• Inspection: examination of a product design, the product itself, a process or an installation, and determination of its conformity with specific requirements based on normative documents or with general requirements using normative criteria or expert judgement.
• Audit: a systematic, documented process for obtaining information and evaluating it objectively to determine the extent to which specified requirements are fulfilled.

These methods provide the operational basis for conformity assessment.

Review, decision and attestation

Conformity assessment comprises several successive steps:

• Review: verification that the selection and determination activities and their results are suitable, adequate and effective.
• Decision: establishing whether conformity has been correctly demonstrated.
• Attestation: a formal determination of whether the requirements have been fulfilled. This takes the form of either a declaration (attestation by the supplier itself) or certification: attestation by a third party (certification body) relating to products, processes, systems or persons.
• Accreditation: attestation of a conformity assessment body’s competence by a third party.
• Surveillance: regular, systematic conformity assessment to maintain the validity of a statement.
• Competence (according to DIN EN ISO/IEC 17021): the ability to apply knowledge and skills to achieve intended results. Competence in particular is a central factor in confidence in conformity assessments.

Although not explicitly mentioned in the standard, testing and inspection reports issued by accredited bodies also contain statements of conformity in practice.

The functional approach to conformity assessment

DIN EN ISO/IEC 17000 describes conformity assessment as a structured process. It comprises:

• Selection of suitable samples
• Determination of conformity
• Review of the results
• Decision on conformity
• Attestation of conformity
• Surveillance, where applicable

This systematic approach ensures that statements of conformity are traceable, reproducible and reliable.

Practical context and significance

The work of accredited testing laboratories, inspection bodies, certification bodies and accreditation bodies therefore always concerns conformity assessments. These differ primarily in:

• the complexity of the object of conformity assessment,
• the extent to which they follow the systematic approach of DIN EN ISO/IEC 17000,
• the degree of confidence in the conformity assessment body’s independence, impartiality and integrity.

This makes clear that conformity assessment is not merely a formal process, but the basis for reliable technical decisions and market confidence.

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Further information: Part 2 of the series “Conformity assessments in materials testing”: “Conformity assessment by the supplier: responsibility and requirements”.(opens in new tab)