In General, graphical displays should:
Show data
Induce the viewer to think about the substance rather than about the methodology, design or technique of the production
Avoid distortion
Present many numbers in a small space
Make large data sets coherent
encourage the eye to compare different peices of data
reveal data at several levels--from broad to fine
serve a clear purpose--describe,explore, tabulation or decoration
be closely integrated with verbal/writen descriptions
"Graphics reveal data." p.13
Graphical excellence is the efficient communcation of complex quantitative ideas. p15
"Time-series displays are at their best for big dat sets with real variability. Why waste the power of data graphcs on simple linear changes, which can be better summarized with one or two numbers? Instead, graphics should be reserved for the richer, more complex, more difficult statistical material." p 30
"...small, non-comparitive, highly labeled data sets usually belong in tables." p 33
The Small Multiple: a closely spaced group of graphs that use the same design technique to show changes in data. p42
"The relational graphic...is the greatest of all graphical designs." p47
Principals of Graphical Excellence:
Graphical excellence isthe well-designed presentation of interesting data--a matter of substance, of statistics, and of design.
graphical excellence consists of complex ideas communicated with clarity, percision and effieciency
graphical excellence is that which gives the viewer the greatest number of ideas in the shortest time with the least ink in the smallest space.
graphical excellence is almost always multivariate
graphical excellence requires telling the truth about data. p51
"Tables usually outperform graphics in reporting on small data sets of 20 numbers or less. The special power of graphics comes in the display of large data sets." p56
Lie Factor = (size of effect shown in graphic) / (size of effect in data) p57
6 Principals of Graphical Integrity:
The representation of numbers, as physically measured on the surface of the graph itself should be directly proportional to the numerical quantities represented
clear detailed and thorough labeling should be used to defeat graphical distortion and ambiguity. write out explainations of the data on the graphic itself. albel important events in the data.
Show data variation, not design variation.
in time-series displays of money, deflated and standardized unites of monetary measurements are nearly always better than nominal units.
the number of information-carrying (variable) dimensions depicted should not exceed the number of dimensions in the data.
Graphjics must not quote data out of context.
5 Principals in the Theory of Data Graphics:
Above all else, show the data.
Maximize the data-ink ratio.
Erase non-data-ink.
Erase redundant data-ink.
Revise and edit.
"Graphics can be designed to have at least 3 viewing depths: 1. what is seen from a distance, an overall structure usually aggregated from an underlying microstucture; 2. what is seen up close and in detail, the fine structure of the data; and 3. what is seen implicetly, underlying the graphic--that which is behind the graphic." p155
"Different visual angles for different aspects of th data also organize graphical information. Each separate line of sight should remain unchanged (perferably horizontal or verical) as the eye watches for data variation off the flat of the line of sight. For multivariate work, several clear lines can be created." p 155
Small Multiples:
inevitably comparative
deftly multivariate
shrunken, high-density graphics
usually based on a large data matrix
drawn almost entirely with data-ink
efficient in interpretation
often narrative in content, showing shifts in the relationship between variables as the index variable changes (thereby revealing interaction or multiplicative effects).p175
"Maximize data density and the size of the data matrix, within reason." p168
"Graphical elegance is often found in simplicity of design and complexity of data." p177
"Visually attractive graphics also gather their power from content and interpretations beyond the immediate display of some numbers. The best graphics are about the useful and important, about life and death, about the universe. Beautiful graphics do not traffic with the trivial." p 177
Attractive displays of statistical information:
have a properly chosen format and design
use words, numbers and drawing together
reflect balance, a proportion, a sense of relevant scale
displayu an accessible complexity of detail
often have a narrative quality, a story to tell about the data,
are drawn in a professional manner, with the technical details of production done with care,
avoid content-free decoration, including chart-junk. p177
"A table is almost always better than a dumb pie chart...Given their low data density and failure to order numbers along a visual dimension, pie charts should never be used." p178
"Tables also work well when the data presentation requires many localized comparisons...one supertable is far better than a hundred little bar charts." p179
The principle of data/text integration is: Date graphics are paragraphs about data and should be treated as such. p181
"Tables and graphics should be run into the text whenever possible." p181
"Words should tell the viewer how to read the design and not what to read in terms of content." p182
The Friendly Data Graphic:
words are spelled out , mysteries and elaborate encoding avoided
words run from left to right, the usual direction for reading occidental languages
little messages help explain data
elaborately encoded shadings, cross-hatching, and colors are avoided; instead labels are placed on the grapihc itself;no legend is required
graphic attracts viewer, provokes curiosity
colors if used, are chosed so that the color-deficient and color-blind can make sense of the graphic
type is clear, precise, modest; lettering may be done by hand
type is upper-and-lower case, with serifs
Unfriendly data graphics:
abbreviations abound, requiring the viewer to sort throuigh text to dcode abbreviations
words run vertically, particularly along the Y-axis; words run in serveral different directions
graphics is cryptic, requires repeated references to scattered text
obscure codings require going back and forth between legend and graphic
graphic is repellent, filled with chart-junk
design insensitive to color-deficient viewers; red adn green used for essential contrasts
type is clotted, overbearing
type is all capitals, sans serif p183
"Graphics should tend toward the horizontal, greater in length than in height" p186
The "Golden Rectangle" is 1:1.618 or a/b = b/(a+b) p189
General rules:
If the nature of the data suggests the shape of the graphic, follow that suggestion
otherwise, move toward horizontal graphics about 50 percent wider than tall. p190
Well written article.
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