# Difference Map Readability for Dynamic Graphs

## Daniel Archambault, Helen C. Purchase and Bruno Pinaud

### Abstract

Difference maps are one way to show changes between timeslices in a dynamic graph. They highlight, using colour, the nodes and edges that were added, removed, or persisted between every pair of adjacent timeslices. Although some work has used difference maps for visualization, no user study has been performed to gauge their performance. In this paper, we present a user study to evaluate the effectiveness of difference maps over presenting the evolution of the dynamic graph over time on three interfaces. We found evidence that difference maps produced significantly fewer errors when determining the number of edges inserted or removed from a graph as it evolves over time. Also, difference maps were significantly preferred on all questions.

This webpage contains supplimentary material to illustrate all conditions, factors and questions. To read the final version of the paper please click here and here for the slides used during the conference.

### Table of Condition x Factor Examples for Experiment

 Animation Slide Show Small Multiples Without Difference Map Q1: th2 - Blue, vd - Red Q2: th2 - Red, vd - Grey Q3: th2 - increase, vd -fluctuate Q4: th2 - Yellow, vd - blue Q1: th2 - Blue, vd - Red Q2: th2 - Red, vd - Grey Q3: th2 - increase, vd -fluctuate Q4: th2 - Yellow, vd - blue Q1: th2 - Blue, vd - Red Q2: th2 - Red, vd - Grey Q3: th2 - increase, vd -fluctuate Q4: th2 - Yellow, vd - blue With Difference Map Q1: th2 - Blue, vd - Red Q2: th2 - Red, vd - Grey Q3: th2 - increase, vd -fluctuate Q4: th2 - Yellow, vd - blue Q1: th2 - Blue, vd - Red Q2: th2 - Red, vd - Grey Q3: th2 - increase, vd -fluctuate Q4: th2 - Yellow, vd - blue Q1: th2 - Blue, vd - Red Q2: th2 - Red, vd - Grey Q3: th2 - increase, vd -fluctuate Q4: th2 - Yellow, vd - blue

If you want to play the videos under Windows XP with Windows Media Player, you need to install a codec pack first. The one at http://www.free-codecs.com/download/ffdshow.htm (use the "Download FFDShow MPEG-4" link). seems to work fine.