What is the KSA scheme (Criteria, Standards, Attributes) and how does this principle work?

The CSA scheme (Criteria, Standards, Attributes) is a structured approach to defining and assessing the quality of software or other products. It is used to formalize product requirements and ensure their clarity, measurability, and verifiability.

• Criteria: High-level quality characteristics that are important to the user or stakeholder. They describe what should be achieved. Examples: Functionality, Reliability, Ergonomics, Performance, Security.
• Standards: More specific, measurable, and verifiable requirements that detail the criteria. They define how quality should be achieved. Standards should be unambiguous. Examples: Response time of the form within 2 seconds, Successful request share of at least 99.9%, Use of OAuth 2.0 authorization.
• Attributes: Detailed characteristics or properties that confirm compliance with standards. They are usually objective and quantitative. Examples: Specific response time value (e.g., 1.5 sec), Number of errors in logs over a certain period, Presence of a field for entering a one-time code from SMS.

The principle of CSA is to decompose high-level requirements (Criteria) into more specific and verifiable ones (Standards and Attributes). This allows:

• Clearly define expectations from the product.
• Develop measurable indicators for quality assessment.
• Structure the testing process, focusing on specific standards and attributes.
• Ensure a common understanding of quality requirements among all project participants.

For example:

Criterion	Standard	Attribute
Performance	Page load time no more than 3 seconds	Time measured from request to full rendering
Reliability	99% successful transactions	Share of transactions without errors per day
Functionality	Correct addition of a product to the cart	Presence of the item in the cart after clicking "Add"