In the realm of dependability engineering, particularly when dealing with safety and reliability, the concepts of verification and validation (often referred to as V&V) are critical for ensuring that a system or product meets its intended goals. Though frequently used together, these terms have distinct meanings and purposes that are essential to understand when assessing the quality and functionality of a system.
Verification: Ensuring Compliance with Specifications
The primary goal of verification is to ensure that the system or product conforms to its design specifications and technical requirements. Verification is concerned with checking whether the system has been built according to the design and development processes that were outlined during the initial phases of the project. This process seeks to establish whether every aspect of the system is correctly implemented, following the established rules, guidelines, and procedures.
Verification activities typically occur throughout the entire development lifecycle. As each stage of development progresses, verification tasks help ensure that the product remains aligned with its predefined specifications. This includes reviewing documents, conducting simulations, inspecting the design, and performing tests at various levels of the system, from individual components to full subsystems.
For instance, in the case of a safety-critical system, such as a software application controlling an industrial process, verification would involve ensuring that every piece of code adheres to the technical specifications. The process would guarantee that the software modules are correctly developed and do not deviate from the architecture laid out in the planning stages.
Validation: Ensuring Fitness for Purpose
While verification focuses on conformity to design, validation shifts attention to the end-user needs and the actual performance of the system in real-world conditions. In other words, validation answers the question: Does the system meet the real-world needs and requirements of its users?
Validation typically takes place toward the end of the development process, once the system is complete or nearly complete. It involves evaluating the system in a real or simulated environment that mirrors its final operational context. The goal is to confirm that the system performs the function for which it was intended and that it can operate effectively in its actual environment of use.
For example, if a new automated safety system is being designed for a manufacturing plant, validation would involve testing the system under operational conditions to determine whether it performs reliably and meets safety standards. This might include stress testing the system in a live environment, conducting performance trials, and obtaining feedback from users to ensure it fulfills its intended role.
A Distinction with Significant Implications
The difference between verification and validation can be summarized by two key questions:
- Verification asks, “Have we built the system correctly?” This refers to whether the system adheres to its design specifications and whether each element is implemented according to plan.
- Validation asks, “Have we built the right system?” This question focuses on whether the system delivers the expected value and utility to the end user, ensuring that it meets the broader requirements for which it was developed.
Balancing Verification and Validation
Both verification and validation are necessary for achieving a high level of dependability in systems, especially in safety-critical fields such as aerospace, healthcare, and industrial automation. Relying solely on verification may lead to a system that is technically sound but does not address real-world user needs, while focusing only on validation could result in a system that satisfies user needs but contains technical flaws.
By incorporating both verification and validation throughout the development lifecycle, engineers and developers can ensure that not only is the product technically accurate, but it is also fit for purpose in its intended environment. In the context of safety, this dual approach is crucial, as it minimizes the risks associated with both functional failures and unmet user expectations.