DiffPin: Interactive Specification of References for Comparative Small-Multiple Displays

Abstract

Small-multiple displays are frequently used for visual comparison by juxtaposition. Explicitly encoding differences between cells enables to convey also minor differences in the data, but requires to specify references for the comparison which is non-trivial in views with a complex layout. This paper proposes DiffPin - an interaction technique to flexibly specify references for cells in small-multiple views. DiffPin enables an easy and fast specification of references on different levels of the visualization (e.g. cell, row, column), even in complex small-multiple views containing nested axes or subtotals. The paper provides considerations for visual encodings in comparative small-multiple displays using DiffPin, and proposes strategies for visually discriminating reference data from compared data for specific visualization types. Initial qualitative user feedback indicates that users are intuitively able to use the provided interactions to quickly and efficiently perform comparative tasks.