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Verification and validation

Methods for checking conformance to requirements

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In reality, as quality management terms, the definitions of verification and validation can be inconsistent. Sometimes they are even used interchangeably.

However, the PMBOK guide, a standard adopted by the Institute of Electrical and Electronics Engineers (IEEE), defines them as follows in its 4th edition:

  • "Validation. The assurance that a product, service, or system meets the needs of the customer and other identified stakeholders. It often involves acceptance and suitability with external customers. Contrast with verification."
  • "Verification. The evaluation of whether or not a product, service, or system complies with a regulation, requirement, specification, or imposed condition. It is often an internal process. Contrast with validation."

Similarly, for a Medical device, the FDA (21 CFR) defines Validation and Verification as procedures that ensures that the device fulfil their intended purpose.

  • Validation: Ensuring that the device meets the needs and requirements of its intended users and the intended use environment.
  • Verification: Ensuring that the device meets its specified design requirements

ISO 9001:2015 (Quality management systems requirements) makes the following distinction between the two activities, when describing design and development controls:

  • Validation activities are conducted to ensure that the resulting products and services meet the requirements for the specified application or intended use.
  • Verification activities are conducted to ensure that the design and development outputs meet the input requirements.

It also notes that verification and validation have distinct purposes but can be conducted separately or in any combination, as is suitable for the products and services of the organization.

The National Institute of Standards and Technology Information Technology Laboratory Computer Security Resource Center has a variety of definitions for both validation and verification

  • Validation - The first definition indicates confirmation (through the provision of strong, sound, objective evidence) that requirements for a specific intended use or application have been fulfilled. However, within the family of definitions, it is frequently used in a manner synonymous with verification.
  • Verification - often used to indicate a persona or identity has been verified against a database, such as a PIN-protected identify certificate matches a controlled access list.

Overview

Verification

Verification is intended to check that a product, service, or system meets a set of design specifications. In the development phase, verification procedures involve performing special tests to model or simulate a portion, or the entirety, of a product, service, or system, then performing a review or analysis of the modeling results. In the post-development phase, verification procedures involve regularly repeating tests devised specifically to ensure that the product, service, or system continues to meet the initial design requirements, specifications, and regulations as time progresses. It is a process that is used to evaluate whether a product, service, or system complies with regulations, specifications, or conditions imposed at the start of a development phase. Verification can be in development, scale-up, or production. This is often an internal process.

Validation

Validation is intended to ensure a product, service, or system (or portion thereof, or set thereof) results in a product, service, or system (or portion thereof, or set thereof) that meets the operational needs of the user. For a new development flow or verification flow, validation procedures may involve modeling either flow and using simulations to predict faults or gaps that might lead to invalid or incomplete verification or development of a product, service, or system (or portion thereof, or set thereof). A set of validation requirements (as defined by the user), specifications, and regulations may then be used as a basis for qualifying a development flow or verification flow for a product, service, or system (or portion thereof, or set thereof). Additional validation procedures also include those that are designed specifically to ensure that modifications made to an existing qualified development flow or verification flow will have the effect of producing a product, service, or system (or portion thereof, or set thereof) that meets the initial design requirements, specifications, and regulations; these validations help to keep the flow qualified. It is a process of establishing evidence that provides a high degree of assurance that a product, service, or system accomplishes its intended requirements. This often involves acceptance of fitness for purpose with end users and other product stakeholders. This is often an external process.

It is sometimes said that validation can be expressed by the query "Are you building the right thing?" and verification by "Are you building it right?". "Building the right thing" refers back to the user's needs, while "building it right" checks that the specifications are correctly implemented by the system. In some contexts, it is required to have written requirements for both as well as formal procedures or protocols for determining compliance.

It is entirely possible that a product passes when verified but fails when validated. This can happen when, say, a product is built as per the specifications but the specifications themselves fail to address the user's needs.

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