PRISE: A process to support iStar extensions

iStar is a goal-based requirement modelling language, being used both in industrial and academic projects of different domains. Often the language is extended to incorporate new constructs related to an application domain or to adjust it to practical situations during requirements modelling. These iStar extensions have been proposed in an ad hoc way resulting in many problems of incompleteness, inconsistency and conflicts. Recently, the language was standardised, but it continues being extended. Thus, we consider that this is an adequate moment to study how to support the proposals of the next iStar extensions. In this paper, we define PRISE, a process to support the creation of iStar extensions which is driven by model-based development concepts, reuse of existing iStar extensions and guidelines of experts. This process can be customised. We illustrate the usage of PRISE by recreating five existing iStar extensions. Finally, we evaluated PRISE with interviews and a survey with experts; and, we performed an interview to analyse the opinion about the usage of the PRISE to create a new iStar extension by a novice. The evaluation and validation indicate good results to avoid problems and increase the quality of the proposals and well receptivity by the experts and novice.