4. Conclusion

So, when customer feedback does not indicate a preponderance of the "difficulty of use" criterion, or indeed of any of the criteria taken into account, the techniques in the first part of the article (§ ), involving questionnaires, are a priori the most suitable.

When some variables are clearly more important than others, one possible solution is to weight and aggregate the different variables using techniques adapted to the problem under consideration [11], and therefore not necessarily corresponding to the various conventional weighted averages.

In situations where "difficulty of use" is one of the real determining factors in the act of purchase, it is interesting to approach the techniques in the second part of the article, which are entirely focused on the study of this variable. Difficulty of use" is not "drowned out"...