Just Because You Can Doesn\'t Mean You Should - Graphing Data Well

Steve Figard, Ph.D., Abbott Laboratories, Abbott Park, IL Just Because You Can, Doesn’t Mean You Should – The Elements of Graphing Data Well

Agenda/Objectives of Presentation ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],“ When a graph is made, quantitative and categorical information is encoded by a display method. Then the information is visually decoded. This visual perception is a vital link. No matter how clever the choice of the information, and no matter how technologically impressive the encoding, a visualization fails if the decoding fails . Some display methods lead to efficient, accurate decoding, and others lead to inefficient, inaccurate decoding.” - William Cleveland ,[object Object],[object Object]

Terminology ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],aka, y axis aka, x axis

Terminology ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],How relate to log 2 ? Now these numbers we understand!

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],The raw data: interesting but not as informative… … as the actual difference between the lines.

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],The optical illusion: The lines are only one unit apart across the entire range. Why? Because the eye is good at perceiving perpendicular distances between two curves, but not the difference in height. Lesson to be learned: plotting the metric of interest may be more Informative than the raw data.

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],“ Get your facts first, and then you can distort them as much as you please. (Facts are stubborn, but statistics are more pliable).” - Mark Twain

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],one year interval five year interval

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],JMP is particularly good at allowing “ on the fly” adjustment of axes

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],JMP provides several sets of markers that should be evaluated with this commandment in mind

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Anyone recognize Excel bar chart options here?! The moiré effect describes the phenomenon when the graphic design interacts with the physiological tremor of the eye to generate the distracting appearance of vibration and movement.

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Can you say “garish”?! garish adj . 1 too bright or gaudy; showy; glaring 2 gaudily or showily dressed, decorated, written, etc. (Webster’s New World College Dictionary, 4 th Ed.)

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],“ When a graphic is taken over by decorative forms or computer debris, when the data measures and structures become Design Elements, when the overall design purveys Graphical Style rather than quantitative information, then that graphic may be called a duck in honor of the duck-form store, ‘Big Duck.’” - Edward Tufte Based on an architectural observation that is valid for graphics: “ It is all right to decorate construction but never construct decoration.” Fortunately, this is really hard to do in JMP…you have to work at it. Our Worst case selection will further clarify this rule of thumb.

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Five different vertical scales are used to show the price and two different horizontal scales to show the passage of time without one indication of these changes (not even a scale break)! (FYI: This qualifies as a “self-promoting graphical duck.”)

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Some data that doesn’t fit the pattern, an important observation, is actually obscured by the Marching Band…

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Data-ink ratio up to ~ 0.9 All data clearly visible

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],This map of France was originally 27 square inches (close to that of previous slide). It shows the location and boundaries of 30,000 French communes. To recreate the data of the map would require somewhere in the neighborhood of 240,000 numbers: 30,000 latitudes, 30,000 longitudes, and an average of six numbers describing the shape of each commune. The data density thus works out to be nearly 9,000 numbers per square inch.

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Simplest: height by weight…

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Wrap by sex:

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Adding overlay by age: Eh, don’t like that? Hit undo button twice…

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Redo by reversing the process use: wrap by age overlay by sex… And if you still don’t like it or see clearly the story in the data, UNDO…REDO!

The Ten Commandments…of good graphics ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],The concept that “the simpler the form of a letter the simpler its reading” was an obsession of beginning constructivism. It became something like a dogma, and is still followed by “modernistic” typographers…. Ophthalmology has disclosed that the more the letters are differentiated from each other, the easier is the reading . Without going into comparisons and details, it should be realized that words consisting of only capital letters present the most difficult reading – because of their equal height, equal volume, and with most, their equal width. When comparing serif letters with sans-serif, the latter provide an uneasy reading . The fashionable preference for sans-serif in text shows neither historical nor practical competence.

A Word about PowerPoint ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Guilty as charged?

A Word about PowerPoint ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Competitors for Best & Worst ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Plots 6 (!) variables: 1. size of army 2/3. location on 2D surface 4. direction of movement 5. temperature 6. dates during retreat (time) … defies “the pen of the historian by its brutal eloquence.” Invasion starts with 422,000 men at Polish-Russian border A sacked and deserted Moscow reached with only 100,000 men Retreat in dead of winter depicted on lower darker band and linked to temp scale and dates on bottom Only 10,000 made it home!

Competitors for Best & Worst ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Only five pieces of data (not variables) in this “ graphically preposterous” work of art. Colors signify nothing …” delighted connoisseurs of the graphically preposterous.” Not one but two axis breaks! 3D effect = chartjunk Since numbers all sum to 100%, plotting both is redundant.

Conclusion (in Tufte’s words) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Handy References ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Just Because You Can Doesn\'t Mean You Should - Graphing Data Well

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Editor's Notes