Mean Time to Detection (MTTD)
The mean time to detection metric is used to identify how long it takes to detect problems that arise. Sometimes even missing a very small issue can have a significant impact on the overall solution. Robust monitoring mechanisms can be implemented to constantly observe software functions and availability, and to detect problems as quickly as possible. A lower MTTD value is an indication that effective monitoring and detection mechanisms are in place so that errors are ideally detected and fixed before users even notice them.
The MTTD metric is measured during the QA and Operate phases.