In the literature on multi-criteria group decision support, many
methods have been discussed. In general, these methods are based on
collective aggregation functions that, through the judgments given by
each decision maker on the actions according to each criterion, must
determine an action that is the best or that represents a consensus.
In some cases, the application of these methods is either complicated
in use and others can also generate controversial results because of the
weighted average they use.

geometric mean, median, collective aggregation function