Showing papers on "Choropleth map published in 1997"
TL;DR: In this article, a combination of a review of previous color research and an experiment designed to test specific combinations of colors on maps, criteria were established and evaluated for selecting colors for choropleth maps of mortality data.
Abstract: Use of color for representing health data on maps raises many unanswered questions. This research addresses questions about which colors allow accurate map reading and which colors map users prefer. Through the combination of a review of previous color research and an experiment designed to test specific combinations of colors on maps, criteria were established and evaluated for selecting colors for choropleth maps of mortality data. The color-selection criteria provide pairs of hues for diverging schemes that avoid naming and colorblind confusions. We also tested sequential and spectral schemes. Our results show that color is worth the extra effort and expense it adds to map making because it permits greater accuracy in map reading. In addition, people prefer color maps over monochrome maps. Interestingly, scheme preference is affected by levels of clustering within mapped distributions. In this research, people preferred spectral and purple/green hue combinations. Contrary to our expectations, spectral ...
154 citations
1 Jan 1997
TL;DR: The format of the geographical database and the steps involved in constructing one are described, illustrated by the experience in creating a database for the coastlines and national political boundaries of the world.
Abstract: The map() function in S permits a wide range of line and filled area maps to be drawn for use with map-oriented data analysis. The data underlying these maps is stored in a geographical database. This report describes the format of the geographical database and the steps involved in constructing one. The process is illustrated by our experience in creating a database for the coastlines and national political boundaries of the world. The world database allows data to be displayed on a map of the entire world or on smaller subsets such as Europe or individual countries. The data comes from the World Data Bank II (US Dept. of Commerce) but we have performed edits to correct digitizing errors and have added accurate descriptions of the polygonal regions that make up each country. Because the database contains polygonal information, choropleth maps can be drawn that use data values to control the color of regions, and because it is so detailed, maps can be made in a wide range of scales.
26 citations
1 Apr 1997
TL;DR: Several types of statistical maps used for environmental analysis were chosen to show the advantages, disadvantages, and data limitations of each.
Abstract: The Environmental Restoration Project at Los Alamos National Laboratory (LANL) has over 11,000 sampling locations in a 44 square mile area. The sample analyses contain raw analytical chemistry values for over 2,300 analytes and compounds used to define and remediate contaminated areas at LANL. The data consist of 2.5 million records in an oracle database. Maps are often used to visualize the data. Problems arise when a client specifies a particular kind of map without fully understanding the limitations of the data or the map. The ability of maps to convey information is dependent on many factors, though all maps are data dependent. The quantity, spatial distribution, and numerical range of the data can limit use with certain kinds of maps. To address these issues and educate the clients, several types of statistical maps (e.g., choropleth, isarithm, and graduated symbol such as bubble and spike) used for environmental analysis were chosen to show the advantages, disadvantages, and data limitations of each. By examining both the complexity of the analytical data and the limitations of the map type, it is possible to consider how reality has been transformed through the map, and if that transformation accurately conveys the information present.