Wikipedia defines evaluation as "systematic determination of merit, worth, and significance of something using criteria against a set of standards". In ITIL we evaluate the effects of a service change and any of the unintended effects to help Change Management make effective decisions as to whether changes should be approved or not.
In reality, it's easy to predict the intended effects because those are what we expect to occur. The unintended effects are much harder to predict and in some cases are not even seen until the service change is actually implemented and we're in production already.
As with most ITIL practices, evaluation is concerned with value. If used effectively, evaluation will deliver benefit from informed decisions from Change Management and the future services delivered. Continual Service Improvement also feeds from our evaluation at the transition stage to enhance future predictions and performance.
Which modelEvaluation uses the (PDCA) model:
We want to consider- Predicted performance
- Actual performance
- Risk
Inputs for evaluation process- Service package
- SDP
- Test results and analysis/report
Outputs from evaluation process- Evaluation report (for Change Management)