What metric is often used to assess a system’s reliability?

What metric is often used to assess a system’s reliability?

• A. Mean Time Between Failures (MTBF)
• B. System Usability Scale (SUS)
• C. Cost per Test
• D. Test Coverage Ratio

Answer: (A)

Mean Time Between Failures (MTBF) is a critical metric used to measure the reliability of a system. It quantifies the average time elapsed between inherent failures of a system—basically, how long a system can be expected to operate before failing. This metric is particularly valuable because it provides a direct indication of the reliability of the system in question; a higher MTBF suggests a more reliable system, while a lower MTBF indicates that failures are likely to occur more frequently.

In contrast, the other options serve different purposes and are not directly related to assessing reliability. The System Usability Scale (SUS) focuses on evaluating user-friendliness and satisfaction with a system's usability, rather than its reliability. Cost per Test is primarily concerned with the financial aspect of testing rather than how dependable a system is during operation. Lastly, Test Coverage Ratio pertains to the extent to which testing has evaluated the system's functionalities, which does not inherently measure reliability but rather the thoroughness of tests conducted.

Thus, MTBF stands out as the appropriate metric for directly assessing a system's reliability, making it the right choice in this context.