The Atlas describes and maps every change in the boundaries of all United States counties from the early 1600s to 2000. In addition, the atlas compiles and maps all changes in colonial or territorial and state boundaries, including the evolution of the states, plus county name changes, unsuccessful proposed counties, and attachments of unorganized counties and non-county areas to operational counties. In most cases, a separate map is available for each different county configuration. view maps or Download Historical State and County Shapefiles. Zipped files include maps, database and supplemental texts
a tool that can convert geographic coordinate data from one format to another. If you're not a map nut, that's the challenge one might encounter switching, for example, from latitude and longitude to Universal Transverse Mercator--or from geocentric latit
AktuellERHEBUNG ZUM GISREPORT 2005/2006Derzeit werden für denGIS-Report 2005/2006 die Daten erhoben und den Firmen die KorrekturbögenIhrer Softwareprodukte zugeschickt. Bis 01. Jannuar 2006 erhalten alle FirmeneinenKorrekturlaufIhrer Einträge.Firmen
CartoWeb is a comprehensive and ready-to-use Web-GIS (Geographical Information System) as well as a convenient framework for building advanced and customized applications.
CIESIN, the Center for International Earth Science Information Network, is a unit of the Earth Institute at Columbia University, based at the Lamont campus in Palisades, New York. CIESIN works at the intersection of the social, natural, and information sciences, and specializes in on-line data and information management, spatial data integration and training, and interdisciplinary research related to human interactions in the environment. CIESIN’s mission is to provide access to and enhance the use of information worldwide, advancing understanding of human interactions in the environment and serving the needs of science and public and private decision making.
A. Geronimus, J. Bound, и L. Neidert. Journal of the American Statistical Association, 91 (434):
529--537(июня 1996)Investigators of social differentials in health outcomes commonly augment incomplete microdata by appending socioeconomic characteristics of residential areas (such as median income in a zip code) to proxy for individual characteristics. But little empirical attention has been paid to how well this aggregate information serves as a proxy for the individual characteristics of interest. We build on recent work addressing the biases inherent in proxies and consider two health-related examples within a statistical framework that illuminates the nature and sources of biases. Data from the Panel Study of Income Dynamics and the National Maternal and Infant Health Survey are linked to census data. We assess the validity of using the aggregate census information as a proxy for individual information when estimating main effects and when controlling for potential confounding between socioeconomic and sociodemographic factors in measures of general health status and infant mortality. We find a general, but not universal, tendency for aggregate proxies to exaggerate the effects of micro-level variables and to do more poorly than micro-level variables at controlling for confounding. The magnitude and direction of these biases vary across samples, however. Our statistical framework and empirical findings suggest the difficulties in and limits to interpreting proxies derived from aggregate census data as if they were micro-level variables. The statistical framework that we outline for our study of health outcomes should be generally applicable to other situations where researchers have merged aggregate data with microdata samples..