4. Weighting functions

Comparing the relative importance of functions can help you prioritize your search for alternatives: the less useful a function is, the more you want to reduce its cost. To this end, you can use cross-sorting and weighted voting tools.

It makes sense to distinguish between the functions that are the "raison d'être" of a solution, and those that are the starting point for the search for alternatives. This is why the expression of functions will most often begin with the use phase, followed by the other phases of the life cycle.

However, the process of weighting functions can prove tricky: for example, is respecting a constraint in use more important than ensuring its technical feasibility? Opinions will differ greatly depending on the viewpoints of the stakeholders interviewed. We therefore advise you to avoid this stage: one performance...