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Event sequences are central to the analysis of data in domains that range from biology and health, to logfile analysis and people's everyday behavior. Many visualization tools have been created for such data, but people are error-prone when asked to judge the similarity of event sequences with basic presentation methods. This article describes an experiment that investigates whether local and global alignment techniques improve people's performance when judging sequence similarity. Participants were divided into three groups (basic versus local versus global alignment), and each participant judged the similarity of 180 sets of pseudo-randomly generated sequences. Each set comprised a target, a correct choice and a wrong choice. After training, the global alignment group was more accurate than the local alignment group (98 versus 93 percent correct), with the basic group getting 95 percent correct. Participants' response times were primarily affected by the number of event types, the similarity of sequences (measured by the Levenshtein distance) and the edit types (nine combinations of deletion, insertion and substitution). In summary, global alignment is superior and people's performance could be further improved by choosing alignment parameters that explicitly penalize sequence mismatches.

The analytical derivation of a hypothesis is a process, that requires a transformation of information between raw data and an analytical model. Even though much effort has been spent to support the creation of hypotheses both by algorithmic and visual means, much less research has been done on how the process can be reversed for the verification of existing hypotheses. An evaluation of empirical hypotheses must be grounded in raw data and may require many tedious drill-downs, especially for complex data. We present a concept combining an analytical technique for the representation of hypotheses and their transformation into the data-space. We also show visualization techniques for the formalization of the hypothesis in the analytical space and its visual evaluation in the data space. The evaluation is supported by a visual-matchmaking between original raw data and a modification of this data based upon the assumptions implied by the hypothesis.