when engaging in application performance management, for example in the course of website monitoring, enterprises collect many measurements of the performance of information technology (it) applications. however, this measurement data may not provide a clear and simple picture of how well those applications are performing from a business point of view, a characteristic desired in metrics that are used as key performance indicators. reporting several different kinds of data can cause confusion. reducing measurement data to a single well understood metric is a convenient way to track and report on quality of experience.