Different methodologies exist to foster innovation. The well-known ones are Design Thinking, User-Experience Design and Service Design. What all these methodologies have in common is the user-centered principle and the iterative process. These recommend frequent testing of the product or service under development with users during the innovation process. While these tests are certainly useful, they are not sufficient to properly validate the innovation. Therefore, in this paper, the combination of pre-experimental and quasi-experimental methods is proposed to validate an innovation and its implicit assumption that the innovation corresponds to a problem solving that significantly improves the life of users. In this research, authors demonstrate how to use pre-experiment and quasi-experiment in the design process to validate progress from one iteration to the next. This is illustrated by a case study of an autonomous vehicle as public transportation service for people with disability and reduced mobility in a touristic context.