Re: [NTG-context] Charts, Graphs, Tufte, and ConTeXt

Nicolas Grilly skreiv:

Karl Ove Hufthammer wrote:

...

Yes! R (especially using the new grid and lattice framework) produces excellent charts and graphs, with very sensible default options (much of it based on Cleveland's research).

What is Cleveland's research? Can you provide references on the web?

Cleveland has done much research on graphical perception and the visual decoding of information from data displays. He was one of the first to do actual scientific study on this. Earlier, many people had opinions on various common graphs (e.g., ‘pie charts are bad – I don’t like them’). Cleveland came along and did actual scientific *experiments* to show why some type of graphs were worse than others for presenting data (e.g., ‘humans are very bad at judging angles and very good at judging position along a common scale; that’s why pie charts are terrible and dot plots good at presenting (the same) data’), and he proposed new graphical display *based* on this research. See for example this very interesting and easy to read article: Title: Graphical Perception: Theory, Experimentation, and Application to the Development of Graphical Methods Author(s): William S. Cleveland; Robert McGill Source: Journal of the American Statistical Association, Vol. 79, No. 387. (Sep., 1984), pp. 531-554. Stable URL: http://links.jstor.org/sici?sici=0162-1459%28198409%2979%3A387%3C531%3AGPTEA... Some of Cleveland’s research resulted in novel graphical displays, such as trellis displays, coplots and dot plots, and much of it resulted in improvements to common displays. Unfortunately, many of these smaller improvements and very minor but important details seems to be unknown to people who design graphing software. Let me mention a few (not too exciting) examples: Circles should be used instead of rectangles as plotting symbols, especially with data overlap, because overlapping rectangles still look like rectangles, while overlapping circles look nothing like circles. Cleveland actually recommended a list of plotting symbols (for plotting several groups in one plot) for use in scatterplots; see: Title: A Model for Studying Display Methods of Statistical Graphics Author(s): William S. Cleveland Source: Journal of Computational and Graphical Statistics, Vol. 2, No. 4. (Dec., 1993), pp. 323-343. Stable URL: http://links.jstor.org/sici?sici=1061-8600%28199312%292%3A4%3C323%3AAMFSDM%3... Tick marks should point outwards, not inwards (so they don’t camouflage data). The data rectangle should always be slightly smaller than the scale-line rectangle (the box around the data), again to avoid camouflaging the data. These are just a few (perhaps less interesting) features of graph design that R does correctly, but many other programs (e.g., gnuplot, at least for tick marks and data rectangles) don’t (by default). Much of Cleveland’s research has been summarised in his excellent book W.S. Cleveland. Elements of Graphing Data. Revised edition. 1994. See also his other book W.S. Cleveland. Visualizing data. 1993. Other articles of his that may be of interest: Title: Graphical Perception and Graphical Methods for Analyzing Scientific Data Author(s): William S. Cleveland; Robert McGill Source: Science, New Series, Vol. 229, No. 4716. (Aug. 30, 1985), pp. 828-833. Stable URL: http://links.jstor.org/sici?sici=0036-8075%2819850830%293%3A229%3A4716%3C828... Abstract: Graphical perception is the visual decoding of the quantitative and qualitative information encoded on graphs. Recent investigations have uncovered basic principles of human graphical perception that have important implications for the display of data. The computer graphics revolution has stimulated the invention of many graphical methods for analyzing and presenting scientific data, such as box plots, two-tiered error bars, scatterplot smoothing, dot charts, and graphing on a log base 2 scale. Title: Graphical Perception: The Visual Decoding of Quantitative Information on Graphical Displays of Data Author(s): William S. Cleveland; Robert McGill Source: Journal of the Royal Statistical Society. Series A (General), Vol. 150, No. 3. (1987), pp. 192-229. Stable URL: http://links.jstor.org/sici?sici=0035-9238%281987%29150%3A3%3C192%3AGPTVDO%3... Abstract: Studies in graphical perception, both theoretical and experimental, provide a scientific foundation for the construction area of statistical graphics. From these studies a paradigm that has important applications for practice has begun to emerge. The paradigm is based on elementary codes: Basic geometric and textural aspects of a graph that encode the quantitative information. The methodology that can be invoked to study graphical perception is illustrated by an investigation of the shape parameter of a two-variable graph, a topic that has had much discussion, but little scientific study, for at least 70 years. Title: The Many Faces of a Scatterplot Author(s): William S. Cleveland; Robert McGill Source: Journal of the American Statistical Association, Vol. 79, No. 388. (Dec., 1984), pp. 807-822. Stable URL: http://links.jstor.org/sici?sici=0162-1459%28198412%2979%3A388%3C807%3ATMFOA... Abstract: The scatterplot is one of our most powerful tools for data analysis. Still, we can add graphical information to scatterplots to make them considerably more powerful. These graphical additions, faces of sorts, can enhance capabilities that scatterplots already have or can add whole new capabilities that faceless scatterplots do not have at all. The additions we discuss here-some new and some old-are (a) sunflowers, (b) category codes, (c) point cloud sizings, (d) smoothings for the dependence of $y$ on $x$ (middle smoothings, spread smoothings, and upper and lower smoothings), and (e) smoothings for the bivariate distribution of $x$ and $y$ (pairs of middle smoothings, sum-difference smoothings, scale-ratio smoothings, and polar smoothings). The development of these additions is based in part on a number of graphical principles that can be applied to the development of statistical graphics in general. -- Karl Ove Hufthammer