Impact Evaluation

“Objective test of what changes have occurred and the extent to which these can be attributed to the policy” [intervention/service]

Magenta Book (2011)
http://gov.uk/government/publications/the-magenta-book

Incremental cost-effectiveness ratio (ICER)

Obtained by dividing the difference between the costs of the two interventions by the difference in the outcomes (i.e., the extra cost per extra unit of effect).