Methods to aggregate impacts and compare options

Methods for aggregation and comparison are not stand-alone methods but usually build on the outcomes of previous steps in the IA process. They help to combine and summarize the evidence and knowledge obtained throughout the process.   

Cost-benefit analysis (CBA) can be carried out to aggregate different types of monetarised costs and benefits of policy options over a certain time period into one single value (NPV). Economic valuation methods may be used to receive a value for effects assigned to a policy option. Cost-effectiveness analysis as a related approach to CBA focuses on the effectiveness of an intervention in terms of achieving a results at the least costs. Multi-criteria analysis in contrast allows for the integration of different categories of effects (monetarised, quantified, qualitative), and on this basis, ranks the policy options assessed.