What aspect does "quality" from performance attributes refer to?

The term "quality" in the context of performance attributes specifically relates to "how well" a system meets its requirements and performs its intended functions. This aspect of quality encompasses the effectiveness, reliability, and overall suitability of the system's output in relation to user requirements and expectations.

Evaluating quality means considering the degree to which the system fulfills its purpose and meets specified criteria, ensuring that the delivered outcomes are satisfactory to stakeholders. Thus, when discussing quality as a performance attribute, it fundamentally reflects the competency and proficiency of the system in achieving its goals, rather than merely the quantity produced, its responsiveness, or how often it operates.

In summary, quality as "how well" directly correlates with the system's performance and user satisfaction, making it a crucial factor in systems engineering.