On Fri, May 8, 2009 at 1:02 PM, Eric Wolf <[email protected]> wrote: > > There's a pretty good literature history on this very subject. One > important thing noted by JJ Flannery as early as 1956 was that if you > scale your circle areas directly proportional to your variable, map > viewers underestimate the values. You have to scale the the circle > areas by a particular factor. > > For example, see: > > Flannery, J.J. (1971) "The relative effectiveness of some common > graduated point symbols > in the presentation of quantitative data." Canadian Cartographer 8,
PDF copy here - http://eric.ed.gov/ERICDocs/data/ericdocs2sql/content_storage_01/0000019b/80/36/7e/cf.pdf Ian _______________________________________________ Geowanking mailing list [email protected] http://geowanking.org/mailman/listinfo/geowanking_geowanking.org
