On Wed, Mar 05, 2008 at 07:34:30PM +0100, Frédéric ZULIAN <[EMAIL PROTECTED]> wrote a message of 19 lines which said:
> Je recherche une application simple pour réaliser des camemberts. Réponse d'informaticien : les camemberts sont une mauvaise idée, d'ailleurs Edward Tufte l'a dit. http://www.usf.uni-osnabrueck.de/~breiter/tools/piechart/warning.en.html Warning against using piecharts This is the output, when you call "piechart --warning", which is my piechart program version 0.10(+): Warning! Piecharts are generally not recommended to visualise information! Use bar- or pointchars instead if the quantities are important. Studies have shown that piecharts are hard to read if you actually have to answer questions about the numbers they represent. They look very pleasing and are used in a lot of places but they do not help to visualise information that well. Analytic thing person will read the percentages or values given on the legend or the chart itself and analyse them in their head. This is mostly because differences in angles are not easy to judge for the human eye and there are a bunch of cases were you make the piechart experience even worse. There are still reasons to use piecharts. In certain situations the raw numbers are not what is need. You might go for a more fancy or slick presentation which does not stress the numbers or the interpretation of them. Some rules to get better piecharts: * Only use them to display 2 up to 6 fraction of one units * The values should to be in the same magnitute * Values shall not be almost the same, differences will be lost * Use colors with high contrasts to each other Edward Tufte [3-5] and Howard Wainer [6] both recommend bar- or pointcharts for the tasks other people would use piecharts for. This program started as an programming example for libplot. After doing more research about visualisation I found that piecharts are a bad idea for scientific data display. Therefore I erected this warning sign as tribute to visualisation scientist, whose words are lost too often in business noise. It also eases my consciousness. You are educated now, ready to approach piecharts with a little bit more scepticism and decide for yourself. Bernhard Reiter, March 2000 Literature: [1] Gary T. Henry. Graphing Data - Techniques for Display and Analysis, volume 36 of Applied Social Research Methods. SAGE Publications, Inc.,1995. [2] Calvin Fischer Schmid. Statistical Graphics - Design Principles and Practices. Wiley, 1983. [3] Edward Rolf Tufte. The Visual Display of Quantitative Information. Graphics Press, PO Box 430, Cheshire, Connecticut 06410, 1983. [4] Edward Rolf Tufte. Envisioning Information, 1990. [5] Edward Rolf Tufte. Visual Explanations - Images and Quantities, Evidence and Narrative, 1997. [6] Howard Wainer. Visual Revelations - Graphical Tales of Fate and De- ception from Napolean Bonaparte to Ross Perot. Copernicus (Springer), 1997. -- Lisez la FAQ de la liste avant de poser une question : http://wiki.debian.org/DebFrFrenchLists Vous pouvez aussi ajouter le mot ``spam'' dans vos champs "From" et "Reply-To:" To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
