Abstract
We present a precise style for the modelling of business processes based on the UML activity diagrams and two controlled experiments to compare this style with a lighter variant. The comparison has been performed with respect to the comprehensibility of business processes and the effort to comprehend them. The first experiment has been conducted at the Free University of Bolzano-Bozen, while the second experiment (i.e., a differentiated replication) at the University of Genova. The participants to the first experiment were Master students and so more experienced than the participants to the replication, who were Bachelor students. The results indicate that: (a) all the participants achieved a significantly better comprehension level with the precise style; (b) the used style did not have any significant impact on the effort; and (c) more experienced participants benefited more from the precise style.