100 Years of Data Visualization – It’s Time to Stop Making the Same Mistakes

I just watched the very informative webinar above from Data Science Central called 100 Years of Data Visualization – It’s Time to Stop Making the Same Mistakes. In it, Andy Cotgreave reviews some data visualization tips from a 1914 book Graphic methods for presenting facts by Willard Brinton that many data visualizers can still learn from. For example:

1. Don’t size by area. We are terrible at comparing relative size by area.
2. Start your axis at zero, unless you’re dealing with relative data.

Andy also recommends slightly (/s) more recent books on data visualization:

• The Visual Display of Quantitative Information.
• Show Me the Numbers: Designing Tables and Graphs to Enlighten.
• Communicating Data with Tableau.

Finally, I thought it would be useful to reproduce here two lists from Brinton’s book. Some of the details are out-of-date, but the spirit of the lessons are still mostly relevant.

CHECKING LIST FOR GRAPHIC PRESENTATIONS

1. Are the data of the chart correct?
2. Has the best method been used for showing the data?
3. Are the proportions of the chart the best possible to show the data?
4. When the chart is reduced in size will the proportions be those best suited to the space in which it must be printed?
5. Are the proportions such that there will be sufficient space for the title of the chart when the chart has been reduced to final printing size?
6. Are all scales in place?
7. Have the scales been selected and placed in the best possible manner?
8. Are the points accurately plotted?
9. Are the numerical figures for the data shown as a portion of the chart?
10. Have the figures for the data been copied correctly?
11. Can the figures for the data be added and the total shown?
12. Are all dates accurately shown?
13. Is the zero of the vertical scale shown on the chart?
14. Are all zero lines and the 100 per cent lines made broad enough?
15. Are all lines on the chart broad enough to stand the reduction to the size used in printing?
16. Does lettering appear large enough and black enough when seen under a reducing glass in the size which will be used for printing?
17. Is all the lettering placed on the chart in the proper directions for reading?
18. Is cross-hatching well made with lines evenly spaced?
19. Can Ben Day work be used advantageously instead of cross- hatching?
20. Do the Ben Day shadings selected have sufficient contrast?
21. Are all instructions for Ben Day work given so that it will be impossible for the engraver to make a mistake?
22. Are dimension lines used wherever advantageous?
23. Is a key or legend necessary?
24. Does the key or legend correspond with the drawing?
25. Is there a complete title, clear and concise?
26. Is the drafting work of good quality?

RULES FOR GRAPHIC PRESENTATIONS

1. Avoid using areas or volumes when representing quantities. Presentations read from only one dimension are the least likely to be misinterpreted.
2. The general arrangement of a chart should proceed from left to right.
3. Figures for the horizontal scale should always be placed at the bottom of a chart. If needed, a scale may be placed at the top also.
4. Figures for the vertical scale should always be placed at the left of a chart. If needed, a scale may be placed at the right also.
5. Whenever possible, include in the chart the numerical data from which the chart was made.
6. If numerical data cannot be included in the chart, it is well to show the numerical data in tabular form accompanying the chart.
7. All lettering and all figures on a chart should be placed so as to be read from the base or from the right-hand edge of the chart.
8. A column of figures relating to dates should be arranged with the earliest date at the top.
9. Separate columns of figures, with each column relating to a different date, should be arranged to show the column for the earliest date at the left.
10. When charts are colored, the color green should be used to indicate features which are desirable or which are commended, and red for features which are undesirable or criticized adversely.
11. For most charts, and for all curves, the independent variable should be shown in the horizontal direction.
12. As a general rule, the horizontal scale for curves should read from left to right and the vertical scale from bottom to top.
13. For curves drawn on arithmetically ruled paper, the vertical scale, whenever possible, should be so selected that the zero line will show on the chart.
14. The zero line of the vertical scale for a curve should be a much broader line than the average co-ordinate lines.
15. If the zero line of the vertical scale cannot be shown at the bottom of a curve chart, the bottom line should be a slightly wavy line indicating that the field has been broken off and does not reach to zero.
16. When curves are drawn on logarithmically ruled paper, the bottom line and the top line of the chart should each be at some power of ten on the vertical scale.
17. When the scale of a curve chart refers to percentages, the line at 100 per cent should be a broad line of the same width as a zero line.
18. If the horizontal scale for a curve begins at zero, the vertical line at zero (usually the left-hand edge of the field) should be a broad line.
19. When the horizontal scale expresses time, the lines at the left- and right-hand edges of a curve chart should not be made heavy, since a chart cannot be made to include the beginning or the end of time.
20. When curves are to be printed, do not show any more co-ordinate lines than necessary for the data and to guide the eye. Lines 34-inch apart are sufficient to guide the eye.
21. Make curves with much broader lines than the co-ordinate ruling so that the curves may be clearly distinguished from the back- ground.
22. Whenever possible have a vertical line of the co-ordinate ruling for each point plotted on a curve so that the vertical lines may show the frequency of the data observations.
23. If there are not too many curves drawn in one field it is desirable to show at the top of the chart the figures representing the value of each point plotted in a curve.
24. When figures are given at the top of a chart for each point in a curve, have the figures added if possible to show yearly totals or other totals which may be useful in reading.
25. Make the title of a chart so complete and so clear that misinterpretation will be impossible.