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Doing the Right Thing Right - Validation and Verification

May 13, 2024

V&VIn the world of software engineering, two terms that often cause some confusion are verification and validation. While they may sound similar, they serve distinct purposes in the development of software products. Here’s a straightforward breakdown to help differentiate between the two and understand their unique benefits.

What is Verification?

Think of verification as the technical quality check phase in software development. It involves various activities like testing, inspection, design analysis, and specification analysis to ensure the software is being built correctly according to the predefined agreements, standards and regulations. Verification is somewhat like proofreading a draft to make sure it is grammatically correct, adheres to the outline provided.

Key Benefits of Verification:

Early Defect Detection: Verification identifies potential issues early in the development process, reducing the likelihood of severe complications later on.
Comprehensive Product Understanding: Engaging in verification from the start helps the development team understand the product and technology more thoroughly.
Minimized Failures: Regular checks during the verification stage decrease the chances of functional bugs and integration problems.
Customer Specification Compliance: Ensures the software is built according to customer needs and specifications.
Used Agile Practices: Refinement, all Acceptance Criteria, Test Driven Development, Test Automation, Continuous Integration, Definition of Done

What is Validation?

Validation, on the other hand, is the functionality check. It focuses on the outcome, whether the product meets the actual needs and anticipated outcome of the end-users. This process happens after the software has passed the verification phase. Validation is akin to the plot is exciting and coherent to the audience. 

Key Benefits of Validation:

Catches Missed Defects: Any issues not found during verification are often caught during validation when the software is tested under real-world conditions.
Outcome Fulfillment: Validation ensures that the software does what it was intended to do, fulfilling the customer’s requirements.
Corrects Misunderstandings: It helps to identify and rectify any misinterpretations of the customer’s needs that occurred during the development phase.
Satisfies Business Needs: Ultimately, validation helps in delivering a product that not only meets but satisfies the business processes and needs of the customers.
Used Agile Practices: many Acceptance Criteria, Behavior Driven Development, Sprint Review, Definition of Done

How do Verification and Validation Differ?

The main difference between verification and validation lies in their focus areas and timing in the  development lifecycle.

Verification is about ensuring the product is built correctly. It's more technical and internal, focusing strictly on whether the software was built as it was supposed to be.
Validation is about ensuring the right product was built for the end-user. It is inherently more subjective, involving real-world application and user acceptance.

In simpler terms, verification asks, "Are we building the product right?"
while validation asks, "Are we building the right product?"

In Scrum we do both -- verification and validation -- within a Sprint. Each Product Backlog item is verified and validated before being demonstrated in the Sprint Review. A good heuristic is to work on PBI in serial, finishing one (getting to Done) before taking on the next one. If you work in parallel on too many, you will have lots of progress but often no business value as nothing is Done at the end of the Sprint. (see my blog about types of efficiencies)

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