SAIT monitors some of our web applications in real-time using a product called New Relic. New Relic is a service that tracks an enormous amount of information useful to both our developers and customers alike. This information helps us diagnose problems, improve application performance and continuously improve our products. The stats you see here are only a small slice of what New Relic tracks. We provide this information so our customers have visibility into the details about their apps that matter most to them.
Each application monitored by New Relic shows a different set of application performance graphs. Each graph has a title that explains what it measures; most of the graph legends are clickable, allowing you to isolate different parameters. Generally speaking, we post things that matter to the customers we code for, including application uptime, average browser response time, APDEX score and a host of other items.
The Apdex method converts many measurements into one number on a uniform scale of 0-to-1 (0 = no users satisfied, 1 = all users satisfied). The resulting Apdex score is a numerical measure of user satisfaction with the performance of enterprise applications. This metric can be used to report on any source of end-user performance measurements for which a performance objective has been defined.
The Apdex formula is the number of satisfied samples plus half of the tolerating samples plus none of the frustrated samples, divided by all the samples:
Apdext = Satisfied Count + (Tolerated Count / 2) / Total Samples
So it is easy to see how this ratio is always directly related to users' perceptions of satisfactory application responsiveness. To understand the full meaning of the ratio, it is always presented as a decimal value with a sub-script representing the target time T. For example, if there are 100 samples with a target time of 3 seconds, where 60 are below 3 seconds, 30 are between 3 and 12 seconds, and the remaining 10 are above 12 seconds, the Apdex is: 60 + (30 / 2 ) / 100 = 0.75t