An interactive research approach was applied in an evaluation of a potential organizational change for mail carriers. Interviews and observations were performed. The results showed that specialization of mail carriers into either mail sorting or mail delivery would lead to more monotonous jobs. Observations showed that sorting mail in a new district takes substantially more time than in a well-known district. An interactive research approach creates a participative collaboration between employers, union representatives and researchers within a project. This influences the choice, planning and execution of methods, of which observation is one. Through the interactive discussions, the planning of how, who, when and where to perform the observations can be improved. This contributes to creating better opportunities to obtain valid results. The use of video recordings enables joint analysis, which contributes to higher acceptance of outcomes and results. The overall conclusion is that the combination of an interactive approach and observation methods is a way to improve both methodological validity and higher validity of the results in addition to higher acceptance of the results and subsequent decisions.