Preprint #96-5
GIS, Spatial Statistical Graphics, and Forest Health
by
James J. Majure, Noel Cressie, Dianne Cook and
J\"{u}ergen Symanzik
Abstract
This paper discusses the use of a geographic information systems (GIS),
Arcview 2.1, linked with a dynamic graphics program, XGobi, in the
statistical analysis of spatial data. The link allows multivariate data,
collected at geographic locations and stored in Arcview, to be passed
into XGobi and analyzed dynamically. The connection between the points
in XGobi and the spatial locations from which they were collected is
maintained so that points in either Arcview or XGobi can be brushed and
the corresponding points in the other application identified immediately.
Spatial cumulative distribution functions (SCDFs), spatially lagged
scatter plots, and variogram cloud plots can be displayed in XGobi using
the link. In each type of plot, the connection to the spatial sampling
location is maintained and user interaction can take place in either
application.
The link is used to predict and analyze SCDFs of forest crown health in
the northeastern United States. The SCDFs are predicted from field data
collected as part of the U.S. Environmental Protection Agency's (USEPA)
Environmental Monitoring and Assessment Program (EMAP). The field data are
augmented with concomitant geographic information, including Landsat
Thematic Mapper images, digital elevation models, and population
information, which are used to improve the SCDF prediction.
Copies of preprints are available from the author upon request. Use
the preprint number (located at the top of the page) and
make the request directly to the author, Iowa State
University,
Department of Statistics, Snedecor Hall, Ames, IA 50011-1210.