Vladimir Milev Telerik Corporation Proper usage of data visualization in dashboards and business applications Vladimir Milev Telerik Corporation

Data Visualization tools PM @ Telerik Author bio Vladimir Milev Data Visualization tools PM @ Telerik Products: Silverlight, WPF, WP7, ASP.NET, Winforms MCPD Enterprise Application Developer Blog: http://blogs.telerik.com/vladimirmilev/posts.aspx Twitter: @vmilev

About telerik

Agenda Why is proper data visualization so important? Examples of poor usage of visualization and guidelines for correct usage of data vis.

Why is Data Vis so Important? On May 1st, Osama has been killed. How did the world react to his death?

World response – raw data

World Response – Visualization http://www.nytimes.com/interactive/2011/05/03/us/20110503-osama-response.html

Anscombe’s Quartet Created in 1973 by Francis Anscombe Statistical properties are identical: Mean of X (9.0) and Y (7.5) values are constant Nearly same variances, correlations and regressions I II III IV x y 10 8.04 9.14 7.46 8 6.58 6.95 8.14 6.77 5.76 13 7.58 8.74 12.74 7.71 9 8.81 8.77 7.11 8.84 11 8.33 9.26 7.81 8.47 14 9.96 8.1 7.04 6 7.24 6.13 6.08 5.25 4 4.26 3.1 5.39 19 12.5 12 10.84 9.13 8.15 5.56 7 4.82 7.26 6.42 7.91 5 5.68 4.74 5.73 6.89

Anscombe’s quartet

Data Vis and developers

Data-to-ink Ratio (efficiency of graphs) data to ink = data ink / total ink used for printing data-to-ink = proportion of a graphic’s ink devoted to the non-redundant display of data-information 1 – data-to-ink = ratio of redundant junk ink used for visual flare. Can be erased and no useful data information will be lost. An efficient graphic should have a data-to-ink close to 1

Careful with pie charts Relative size of the pie slices is harder to determine Bar charts are just easier to read in general

Careful with pie charts Because of its shape the pie chart wastes precious screen space

Comparing Values With Pies

In defense of pie charts Not all pie charts are bad! Pie Charts are best at visually illustrating the proportion of a part in relation to the whole Pie charts are also good at showing extremes

Careful with pie charts Worst pie chart in the universe! 

Choosing the right chart for the job Do not show relationships that don’t exist!

Choosing the right chart for the job Show trends with lines, not bars

A word about bar charts

A word about bars Bar graphs should always start at 0! Otherwise the visual ratio between bars is skewed and incorrectly exaggerated.

A note about 3d graphs

Gauges vs Bulletgraph Consider using bullet graphs instead of gauges. Better readability Higher data-to-ink ratio Can be used inside a grid control

Linear vs quadratic change

Linear vs quadratic change The difference between Starbucks and KFC is n. The designer decided to stretch the graphic by n Since it is a logo he decided to stretch in two directions…

Linear vs quadratic change Scaling the area of a graph item results in a quadratic (n2) difference in the data! The solution? If you scale area, use A=n2 A=π*r2

Conclusion

Recommended materials Data Driven Consulting: http://www.datadrivenconsulting.com/feed/ Eager Eyes: http://feeds.feedburner.com/EagerEyes Perceptual Edge: http://www.perceptualedge.com/blog/?feed=rss2 Juice Analytics: http://feeds.feedburner.com/JuiceAnalytics Junk Charts: http://junkcharts.typepad.com/junk_charts/atom.xml

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