9/7/2013 1 Few’s Design Guidance CS 7450 - Information Visualization September 9, 2013 John Stasko Topic Notes Today’s Agenda Fall 2013 CS 7450 2 Stephen Few & Perceptual Edge9/7/2013 2 Stephen Few’s Guidance • Excellent advice for the design of tables and graphs • Page references are from Now You See It • Let’s review some of his recommendations  We explored chapters 1-4 earlier  Today we examine chapters 5-12 Fall 2013 CS 7450 3 Analytic Techniques & Practices • Some examples he has highlighted  Optimal quantitative scales  Reference lines and regions  Trellises and crosstabs  Multiple concurrent views and brushing  Focus and context together  Details on demand  Over-plotting reduction Fall 2013 CS 7450 49/7/2013 3 Add Reference Lines Fall 2013 CS 7450 5 p. 96 More Reference Lines Fall 2013 CS 7450 6 p. 979/7/2013 4 Trellis Display Fall 2013 CS 7450 7 p. 100 Typically varies on one variable Crosstab Fall 2013 CS 7450 8 p. 102 Varies across more than one variable9/7/2013 5 Crosstab Fall 2013 CS 7450 9 p. 103 Multiple Concurrent Views Fall 2013 CS 7450 10 p. 107 Vintage infovis9/7/2013 6 Concurrent Views • He calls such things faceted analytical displays  Sometimes that term is used in other ways in infovis • As opposed to dashboards  They are for monitoring, not analysis Fall 2013 CS 7450 11 Overplotting Fall 2013 CS 7450 12 Too many data points p. 1189/7/2013 7 Overplotting Solutions • Reducing size of data objects • Removing all fill color from data objects • Changing the shape of data objects • Jittering data objects • Making data objects transparent • Encoding the density of values • Reducing the number of values  Aggregating the data  Filtering the data  Breaking the data into a series of separate graphs  Statistically sampling the data Fall 2013 CS 7450 13 Quantitative Data • Fundamental visualization techniques Fall 2013 CS 7450 149/7/2013 8 Time Series Data • Patterns to be shown  Trend  Variability  Rate of change  Co-variation  Cycles  Exceptions Fall 2013 CS 7450 15 Time Series Visualizations • Effective visualization techniques include… Fall 2013 CS 7450 169/7/2013 9 Line Graphs Fall 2013 CS 7450 17 p. 151 When quantitative values change during a continuous period of time When to use: Bar Graphs Fall 2013 CS 7450 18 p. 152 When to use: When you want to support the comparison of individual values9/7/2013 10 Dot Plots Fall 2013 CS 7450 19 When to use: When analyzing values that are spaced at irregular intervals of time p. 153 Radar Graphs Fall 2013 CS 7450 20 When to use: p. 154 When you want to represent data across the cyclical nature of time9/7/2013 11 Heatmaps Fall 2013 CS 7450 21 When to use: When you want to display a large quantity of cyclical data (too much for radar) p. 157 Box Plots Fall 2013 CS 7450 22 When to use: p. 157 You want to show how values are distributed across a range and how that distribution changes over time9/7/2013 12 Animated Scatterplots Fall 2013 CS 7450 23 When to use: p. 159 To compare how two quantitative variables change over time Banking to 45° Fall 2013 CS 7450 24 Same diagram, just drawn at different aspect ratios People interpret the diagrams better when lines are around 45°, not too flat, not too steep p. 1719/7/2013 13 Question Fall 2013 CS 7450 25 p. 172 Which is increasing at a faster rate, hardware sales or software sales? Both at same rate, 10% Log scale shows this Patterns Fall 2013 CS 7450 26 Daily sales Average per day p. 1769/7/2013 14 Cycle Plot Fall 2013 CS 7450 27 Combines visualizations from two prior graphs p. 177 A Story Fall 2013 CS 7450 28 How much wine of different varieties is produced? p. 191-29/7/2013 15 Pareto Chart Fall 2013 CS 7450 29 Shows individual contributors and increasing total 80/20 rule – 80% of effect comes from 20% p. 194 Bump Chart Fall 2013 CS 7450 30 Shows how ranking relationships change over time p. 2019/7/2013 16 Deviation Analysis Fall 2013 CS 7450 31 p. 203 Do you show the two values in question or the difference of the two? Distribution Analysis Views • Histogram • Frequency polygon • Strip plot • Stem-and-leaf plot Fall 2013 CS 7450 329/7/2013 17 Histogram Fall 2013 CS 7450 33 p. 225 Frequency Plot Fall 2013 CS 7450 34 p. 2269/7/2013 18 Strip Plot Fall 2013 CS 7450 35 p. 227 Stem-and-leaf Plot Fall 2013 CS 7450 36 p. 2289/7/2013 19 Comparisons Fall 2013 CS 7450 37 Note how first one’s curve is smooth (not such a noticeable difference). Second one is more noticeable. Same data. p. 234 Correlation Analysis Fall 2013 CS 7450 38 Bleah. How can we clean this up? p. 2769/7/2013 20 Crosstab Fall 2013 CS 7450 39 p. 277 Color Choice in Heatmaps Fall 2013 CS 7450 40 p. 285-7 Argues that black should not be used as a middle value because of its saliency (visual prominence) Some people are red- green color blind too9/7/2013 21 Further Articles Fall 2013 CS 7450 41 Blog Fall 2013 CS 7450 429/7/2013 22 Critique It Fall 2013 CS 7450 43 AJC, July 2010 Reminder • HW 2 due Wednesday  Design a table and a graph  Submit 2 copies Fall 2013 CS 7450 449/7/2013 23 Project • Proposals due next Monday • More ideas • Looking for teammates? Fall 2013 CS 7450 45 What are you Listening to? • Represent music listening histories • What would you want to show? • How might you visualize it? Fall 2013 CS 7450 46 Nice example of a project9/7/2013 24 LastHistory • Visualizing a person’s listening history from last.fm • Want to support  Analysis  Reminiscing • Potential to synchronize with photos and calendar entries from that time Fall 2013 CS 7450 47 Baur et al TVCG (InfoVis) ‘10 Fall 2013 CS 7450 48 Video9/7/2013 25 Fall 2013 CS 7450 49 Upcoming • Multivariate Visual Representations 1  Reading Inselberg ‘97 • Multivariate Visual Representations 2  Reading Keim et al