Abstract. Software-intensive systems become more and more important in our everyday lives. But their increasing complexity makes it difficult to develop and maintain them. This chapter gives an overview of the state of the art of building software-intensive systems and outlines research challenges that have been identified by the InterLink working group “software-intensive systems and new computing paradigms”. 1

Informal analysis of many usability tests suggests that there is regularly one participant that is substantially slower than all the others. Moreover, such outliers are more extreme and more frequent than would be predicted by a normal distribution. We propose using a rational model to explain the outliers and the work described here begins to parameterise the model based on empirical data to provide accurate analyses of user performance. This prediction appears to be correct and the model begins to reflect the outlying performance. Moreover, by using an executable model, we believe that it could be used in future as an analytical tool to help designers improve usability for those users who are struggling the most.

Abstract. Papers in HCI play different roles, whether to inspire, solve industrial problems or further the science of HCI. There is a potential conflict between the different views, and a danger that different forms of validity are assumed by author and reader — deliberately or accidentally. This paper reviews some of the issues in this complex area and makes recommendations. 1