Methodologies for the analysis of usage patterns in information visualization

In this position paper, we describe two methods for the analysis of sequences of interaction with information visualization tools -- log file analysis and thinking aloud. Such an analysis is valuable because it can help designers to understand cognition processes of the users and, as a consequence, to improve the design of information visualizations. In this context, we also discuss the issue of categorization of user activities. Categorization helps researchers to generalize results and compare different information visualization tools.