ENV Envisioning Information Lecture 8 – Good Design – What we can learn from Tufte Ken Brodlie

ENV Tufte Design Principles Give the viewer the greatest number of ideas in the shortest space of time using the least ink in the smallest space Try to maximize the data-ink ratio Try to maximize the data density Show data variation, not design variation Tell the truth about the data

ENV Data Ink Data Ink Ratio = (data-ink) / (total ink to produce graphic) = proportion of ink devoted to non- redundant display of information = 1.0 – proportion of graphic that can be deleted without loss of data-information A low value of data ink ratio!

ENV Exercise How much can be removed from this graphic? –1 –2 –3 –4 –5 –6 Answer at:

ENV Box Plots Even well established techniques can be improved How can a box plot be improved in terms of its data ink ratio?

ENV Scatter Plots How can we improve the data ink ratio for the scatter plot?

ENV Tuftes Range Frame 6

ENV BCS Yearbook 2006 BCS Yearbook contains this diagram… How would you draw this graphic?

ENV Data Density Data density = (number of entries in data matrix) / (size of graph) Low data density!

ENV Exercise Calculate the data density for these two examples –Suppose area is 10 sq units of area Gender, height and weight recorded for 92 students –Density for gender breakdown = –Density for height-weight relationship =

ENV Design Variation Fundamental purpose of a graph is to show changes in the data Design variation – where the same data is displayed differently for decoration - is to be avoided Leads to ambiguity and deception What is wrong with this?

ENV Lie Factor = (Size of effect on graph) / (Size of effect on data) Spot the lie!

ENV Exercise What is the lie factor in this graphic?

ENV Reflection.. But it is not an easy matter Consider this graphic –Rate it for data ink, data density and lie factor Discuss!

ENV Show the Context Remember that integrity is important in data presentation Consider the graph opposite –Conclusions can be very different depending on what is shown Spanish alcohol consumption

ENV Acknowledgements This work is largely inspired by ET – Edward Tufte Thanks to the following web sites: – –