Part of software requirements analysis involves associating a qualification method with each requirement. To do this involves envisioning the system behavior associated with each requirement. As a result, the process helps ensure the requirements are well understood.
The four qualification methods are: analysis, demonstration, inspection, and test. The term "test" is often used to include all four methods.
Analysis: Compliance with requirements is determined by models or by interpreting results using established principles. For example, a design's performance might be analyzed by running simulations.
Demonstration: Compliance with requirements is validated by observing the item in operation.
Inspection: Compliance with requirements is determined by formal examination—think of a building inspection for compliance with the local code.
Test: Compliance with requirements is validated by evaluating or executing an item under controlled conditions, configurations, and inputs in order to observe the response. Results are quantified and analyzed.
The report of requirements by qualification method is a requirements validation matrix. See other requirements management reports.
Testing should be risk-based. How risk is determined depends on the nature of the software. In general, the more critical the software the more formal the risk assessment. Risk assessment is also part of analyzing requirements.
See the page on testability for information on writing well-defined requirements.
Walk the RM trail to learn more about requirements management and traceability.