Posted by mark on February 11th, 2011
Monitor metrics vs. User satisfaction
Monitoring the performance of your website pages generates lots of interesting metrics like resolve time, connect time, time to first byte, DOM-ready, first visual (in real browser monitors) and many more.
These metrics:
- provide insight in what might cause a page being slow,
- shows page load time trends over time,
- can trigger alerts in case of a temporary performance drops,
- show the effect of request originating from different geographical locations, etc, etc.
What these numbers do not say is how this affects the user satisfaction of visitors of your website. This is where the Apdex comes in.
The Application Performance Index (Apdex)
The purpose of the Apdex score is to convert performance metrics into insights about user satisfaction. It allows you to specify a threshold that indicates whether your service is operating satisfactory or not.
See the Apdex website for further information and exact definitions.
WatchMouse and the Apdex score
Next to the WatchMouse Site Performance Index, which combines page load time and downtime in a single metric, we recently introduced the Apdex as a new chart type. Both metrics are also available in the custom PDF reports.
The charts below show the Apdex for one page over time:
The charts can also be used to compare Apdex scores between pages:
These charts can now be interpreted as showing the fraction of satisfied visitors on your site: 0 = no users satisfied, 1 = all users satisfied
Note: To make sure that the Apdex chart is based on valid assumptions, the monitor or monitors you use should fulfil the following condition:
Time-out > First limit * 4
The time-out and first limit can be set in the expert mode of you monitor settings. By default the settings will be Apdex compliant, and a warning will be shown if the settings are not Apdex compliant.
What’s next?
The Apdex charts in the WatchMouse reporting are just a first step in reporting customer satisfaction in terms of performance. Now what I would like to know…
- Are the new Apdex charts useful for you?
- How will you use them in your organisation?
- What else would you like to see related to Apdex?
Please let us know in the comments!
Mark Pors
CTO & co-founder