tirsdag den 4. november 2008

Verification, Validation and Assessment


There is defined three different types of tasks and roles in EN 50126:

"Verification": The "Verificator" checks, if we are ready to move on to the next phase in the V-model.

"Validation": The "Validator" checks whether the physical systems behaves as it was supposed to do, i.e. horizontal tests and checks in the V-model.

"Assessment": The "Assessor" checks, if the processes in the Safety Management System are working as they should, i.e. the Safety Management Circle is turning. The assessor is not performing project tasks, the project would be made without the Assessor.



Figure 11, "Verification and Validation"

Interpretation

The difference between the different types of tasks and roles are not very clear between Verification and Validation.

But if Figure 11 is interpreted very strict, it is possible to identify the different types of tasks you meet in the daily Safety Management Life.

The table below shows some tasks that occur when a train is being prepared for take-over from a Supplier to an Operator:



The explanation to the table above is showed graphically below:



Verification example (no. 1): The task "Inspection check, to see if the train is ready for test driving" is a check, which verifies, that we are ready to move on from phase "Installation" in the V-model to the next phase "System Validation".

Validation example (no. 4): The task "Compile documentation showing fulfilment of safety requirements." is a task, which collects different types of proofs like test protocols and hereby validates that the installed system fulfils the requirements from the specifications.

Assessment example (no. 3): The task "Judgement, whether roles and responsibilities are defined in a safety plan, is a task which controls that a proper Safety plan actually exists for the project. It is not the task to actually write the Safety Plan.

Next chapter >> 2.4 Safety Approval process

Focus on the source (/EN 50126/)

The tasks are shown at Figure 11 (see above) and roles a described in the "Definitions" chapter of EN 50126:

Assessment: The undertaking of an investigation in order to arrive at a judgement, based on evidence, of the suitability of a product.

Validation: Confirmation by examination and provision of objective evidence that the particular requirements for a specific intended use have been fulfilled.
The objective of validation is to demonstrate that the system under consideration, at any step of its development and after its installation, meets its requirements in all respects.

Verification: Confirmation by examination and provision of objective evidence that the specified requirements have been fulfilled.
The objective of verification is to demonstrate that, for the specific inputs, the deliverables of each phase meet in all respects the requirements of that phase.

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