It is important to define an evaluation process to determine the degree of compliance of a system. Evaluation is a control procedure to measure the degree of compliance withf the objectives of a system and continuous improvement as a result of measurements. The following elements are useful for the evaluation a VAN:

Elements of evaluation:

• Features
• Operation
• Product Quality

Documentation requirements prior the evaluation:

• Identification and prioritization of the surveillance system
• System design: development of criteria, data collection, presentation and evaluation.
• Presentation of results

Proposed levels to make an objective evaluation:

To perform an objective evaluation three levels of evaluation are proposed, each of which should be evaluated by this criteria: usefulness, quality and cost. The questions can be adapted on the objectives of the van basis, but there are general questions that should be answered as a result of the evaluation.