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Optimizing the Visual Presentation of Your Data

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Graphs generated by the default settings of graphing software programs often require the user to perform time consuming or difficult visual tasks. Or, the graphs present visual messages that don't support the author's intended message.

The most effective visual displays are created with an understanding of how the brain processes visual information and how people interpret visual patterns.

Published in: Data & Analytics
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Optimizing the Visual Presentation of Your Data

  1. 1. Optimizing the Visual Presentation of Your Data Mary Beth Hasselquist, MD #stc15
  2. 2. Graphs constructed using principles derived from knowledge of visual science present •  the user with easy-to-perform visual tasks and •  a visual message that’s congruent with the intended message. © 2015 Aktiva Design, Mary Beth Hasselquist
  3. 3. Designers encode data. Users visually decode the data. A graph is successful only if the decoding process is effective. Different types of graphs require different tasks to decode the data. © 2015 Aktiva Design, Mary Beth Hasselquist
  4. 4. Position along a common scale Position along identical, nonaligned scales Length Angle Slope Area (and volume) Color value © 2015 Aktiva Design, Mary Beth Hasselquist Decoding tasks from most accurate to least accurate
  5. 5. 605040302010 54.1 12.6 8.6 7.9 7.5 5.3 3.2 0.8 100% Percent A user is able to more accurately decode data from a bar (or column) graph than from a pie chart. © 2015 Aktiva Design, Mary Beth Hasselquist
  6. 6. Column and bar graphs encode data in two ways: •  Length •  Position along a common scale In order to encode the data accurately, column and bar charts must start at zero. © 2015 Aktiva Design, Mary Beth Hasselquist
  7. 7. Incorrect construction! © 2015 Aktiva Design, Mary Beth Hasselquist
  8. 8. This column is 40% as long as this column. This column is 85% as long as this column. 60 50 40 30 20 10 0 10 20 30 40 Predicted probability of adherence (%) Copayment for 30-day supply of statin (USD) Adherence to Statin Medication by Copayment © 2015 Aktiva Design, Mary Beth Hasselquist
  9. 9. 60 50 40 30 20 10 0 10 20 30 40 Predicted probability of adherence (%) Copayment for 30-day supply of statin (USD) Adherence to Statin Medication by Copayment 44 46 48 50 52 54 56 58 60 10 20 30 40 Copayment for 30-day supply of statin (USD) Adherence to Statin Medication by Copayment Predicted probability of adherence (%) If the intended purpose of a graph is to highlight the differences between the variables and a column (or bar) graph doesn’t meet this intended purpose, a point (dot) graph can be used. Point graphs encode data using position along a common scale. © 2015 Aktiva Design, Mary Beth Hasselquist
  10. 10. 5.1% 16.0% The addition of numerals at the top of columns (or the ends of bars) adversely effects decoding of the data. Visually, the addition of numerals lengthens the columns. The left column is about two thirds as tall as the right. The left column is about one third as tall as the right. Visually, these two columns look more like this than this.     © 2015 Aktiva Design, Mary Beth Hasselquist
  11. 11. Gestalt principle of Proximity Items that are closer together will appear to belong together as compared to items that are further away. Comp EPO HMO POS PPO POS w/ca CDHP HDHP Unknown item 1 item 2 item 3 item 4 item 5 item 6 item 7 item 8 item 9 not Comp EPO HMO POS PPO POS w/ca CDHP HDHP Unknow item 1 item 4 item 7 item 2 item 5 item 8 item 3 item 6 item 9 © 2015 Aktiva Design, Mary Beth Hasselquist
  12. 12. Construct graphs so that the visual message is congruent with the intended message. A 10 0 5 15 Study population (%) Treatment No treatment DCB A 10 0 5 15 Study population (%) No treatment Treatment DCB Intended message: Treatment reduces risk compared to no treatment. visually incongruent with intended message visually congruent with intended message © 2015 Aktiva Design, Mary Beth Hasselquist
  13. 13. Whenever possible, construct graphs so that the math is done for the viewer. A 10 0 5 15 Study population (%) No treatment Treatment DCB 3.02.52.01.51.00.50 Absolute Risk Reduction of Treatment B A C D Absolute risk reduction (%) In this graph, users must visually do the math to determine the difference between no treatment and treatment for each category. In this graph, the math has been done for users. © 2015 Aktiva Design, Mary Beth Hasselquist
  14. 14. Employing 3D effects, gradients and shadows is almost always a poor design choice when constructing graphs. © 2015 Aktiva Design, Mary Beth Hasselquist
  15. 15. Design principles •  Use horizontal text within graphs whenever possible for easier reading •  Order categorical data in a way that is instructive, not arbitrary •  Use an appropriate scale © 2015 Aktiva Design, Mary Beth Hasselquist
  16. 16. Hue Saturation Value Color has three dimensions © 2015 Aktiva Design, Mary Beth Hasselquist
  17. 17. Hue has no semantic meaning. Any meaning associated with a given hue is culturally determined. © 2015 Aktiva Design, Mary Beth Hasselquist
  18. 18. Values have semantic meaning. These meanings are universal. Least Most © 2015 Aktiva Design, Mary Beth Hasselquist
  19. 19. Adobe Illustrator default Better © 2015 Aktiva Design, Mary Beth Hasselquist
  20. 20. 3.02.52.01.51.00.50 Absolute Risk Reduction of Influenza-Related Complications 30-Days after Influenza Diagnosis in Children with Chronic Medical Conditions Provided by Antiviral Treatment with Oseltamivir Influenza-related complication Respiratory illness other than pneumonia Otitis media and related complications Pneumonia Hospitalizations— all-cause Hospitalizations— pneumonia-related Hospitalizations— non-pneumonia respiratory illness Absolute risk reduction (%) 3.02.52.01.51.00.50 Absolute Risk Reduction of Influenza-Related Complications 30-Days after Influenza Diagnosis in Children with Chronic Medical Conditions Provided by Antiviral Treatment with Oseltamivir Influenza-related complication Respiratory illness other than pneumonia Otitis media and related complications Pneumonia Hospitalizations— all-cause Hospitalizations— pneumonia-related Hospitalizations— non-pneumonia respiratory illness Absolute risk reduction (%) Use color purposefully and only when it contributes to the effectiveness of the graph. A A C B E D F F E D C B In  this  graph,  color  has  no  intended  purpose     other  than  to  make  the  graph  “colorful.”     The  use  of  mul:ple  colors  degrades  the  pa;ern.   © 2015 Aktiva Design, Mary Beth Hasselquist
  21. 21. Any image created in color must work in grayscale. •  Color documents are often reproduced in grayscale. •  Certain visual information, such as information about figure and ground, is carried to the brain only in grayscale. © 2015 Aktiva Design, Mary Beth Hasselquist
  22. 22. Because the values of some colors are similar, when the chart is reproduced in grayscale, it is difficult to distinguish the different wedges. © 2015 Aktiva Design, Mary Beth Hasselquist
  23. 23. In order for us to easily read, there must be sufficient contrast between figure (text) and ground (background). In order for us to easily read, there must be sufficient contrast between figure (text) and ground (background). In order for us to easily read, there must be sufficient contrast between figure (text) and ground (background). © 2015 Aktiva Design, Mary Beth Hasselquist
  24. 24. Mary Beth Hasselquist, MD mb.hasselquist@gmail.com 206-660-9474 © 2015 Aktiva Design, Mary Beth Hasselquist

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