I've been studying up on service level agreements lately, and I've come across useful resources I want to tell you about.
“Metrics for IT Outsourcing Service Level Agreements” by Ian S. Hayes at Clarity Consulting is a basic introduction to the topic that you may find useful. Mr. Hayes shares five principles in selecting SLA metrics, then explains four major categories of metrics — and the advantages and disadvantages as well as application for each.
I'll share one of his tips here:
Choose measurements that are easily collected.
If the metrics in the SLA cannot be easily gathered, then they will quickly lose favor, and eventually be ignored completely. No one is going to spend an excessive amount of time to collect metrics manually. Ideally, all metrics will be captured automatically, in the background, with minimal overhead; however, few organizations will have the tools and processes in place to do so. A metric should not require a heavy investment of time and money; instead use metrics that are readily available, compromising where possible. In some cases, it will be necessary to devise alternative metrics if the required data is not easily obtainable. For example, measuring whether a newly written program meets published IT standards require an arduous manual review. Conversely, a commercially available metric analysis tool can quickly and automatically calculate the program's technical quality. While the end result is not identical, the underlying goal — motivating enhanced quality — is met at a fraction of the manual cost.
The details you'll find here are useful. Worth reading.