To weight or not to weight?
MCA is a very flexible tool, allowing a wide range of criteria to be incorporated. At the same time, it is possible to reflect different priorities by including additional criteria matching a particular goal. Alternatively, it is possible to add a weighting system to the framework, allowing a greater emphasis on a particular aspect or criterion. However, care needs to be taken when doing this. It is very difficult to achieve agreement across all stakeholders when applying weights, as the principle of weights is often seen as downgrading those aspects which are given lesser weights. Extensive stakeholder consultation and workshopping is usually required to achieve any level of agreement on the weights, which will be on top of getting agreement on the criteria themselves. This can be costly in terms of time and money.
In any case, our experience is that the application of weights rarely changes the results of the assessment significantly. A good project will always be a priority project no matter what weights are used. Our practice is therefore to not apply weights, but instead to undertake sensitivity testing to show that different weighting would make little difference in the end.
How to Use the Results
What an MCA framework can do is reflect a hierarchy of needs. We are all familiar with the concept that humans have basic needs (shelter, water, food) that need to be met before more advanced desires become important. Using an MCA framework can build this in. When comparing different infrastructure sectors, it is possible to reflect that clean water will always be more important than say a basic transport network, which is always more important than leisure facilities.
A good example of this hierarchy was seen in developing the Niue National Transport Strategy, where we were able to explain, using an MCA, why the port was more important than the airport. All fuel comes in through the port, including the fuel for aircraft, meaning that planes would not be able to serve the island, if the port was non-functional.
MCA cannot, however, do everything, and in some circumstances, it can be positively unhelpful. If you want to know more about when not to use MCA, let’s have a chat.
To summarise, Multi-Criteria Analysis is a great tool for infrastructure economists and planners but cannot be used in every situation and will often need to be implemented by experienced practitioners. For another example of how we deploy MCA frameworks, see our COMBO tool.