Application outsourcing engagements are typically governed via specific service agreements that are comprised of a number of SLAs. Metrics are a critical ingredient of an SLA. There are dozens of metrics that could potentially be measured for outsourced application support and maintenance services.
Tackle the Basics First
Days & Hours
Unit of Time – What is a “day”? Does it start in a specific time-zone? Does it include holidays? Does it include weekends?
Define a “day” starting from a specific time-zone such as the time-zone from which most of the application users work. Often, different SLA’s are defined based on different business calendars. For example, you may want 24×7 support for Severity-1 production support, whereas regular business hours may be adequate for requests that are not Severity-1.