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W. Aigner, C. Kainz, R. Ma, S. Miksch:
"Bertin was Right: An Empirical Evaluation of Indexing to Compare Multivariate Time-Series Data Using Line Plots";
Talk: EuroVis 2012, Wien (invited); 2012-06-04 - 2012-06-08.

Line plots are very well suited for visually representing time series. However, several difficulties arise when mul- tivariate heterogeneous time-series data is displayed and compared visually. Especially, if the developments and trends of time-series of different units or value ranges need to be compared, a straight forward overlay could be visually misleading. To mitigate this, visualization pioneer Jacques Bertin presented a method called indexing that transforms data into comparable units for visual representation. In this paper, we want to provide empirical evidence for this method and present a comparative study of the three visual comparison methods linear scale with juxtaposition, log scale with superimposition, and indexing. While for task completion times, indexing only shows slight advantages, the results support the assumption that the indexing method enables the user to perform comparison tasks with a significantly lower error rate. Furthermore, a post-test questionnaire showed that the majority of the participants favor the indexing method over the two other comparison methods.

HCI, Information Visualization, Evaluation