Spatial Metadata and GIS for Decision Support

The proliferation of GZS technology has great& increased the access to and the usage of spatial data. Making maps is relatively easy even for those who do not have much cartographic training. Nonetheless, the concerns for spatial data quality among GZS and spatial data users have just began to sprout, partly because information about spatial data quality is not readily available or useful. Metadata, which refer to data describing data, include the quality and accuracy information of the data. The Federal Geographic Data Committee has proposed content standards of metadata for spatial databases. However, the standards are not adequate to document the spatial variation in data quality in geographic data. This paper argues that information about the quality of spatial data over a geographical area, which can be regarded as spatial metadata, should be derived and reported to help users of spatial data to make intelligent spatial decisions orpolicy formulations. While cartographers focus on the representation of spatial data qualily and statisticians emphasize the quantitative measures of data quality, this paperproposes that GZS are logical tools to assess certain types of error in spatial databases because GZS are widely used to gather, manipulate, analyze, and display spatial data. A framework is proposed to derive several vpes of data quality information using GZS. These fypes of quality information include positional accuracy, completeness, attribute accuracy and to some extent logical consistency. However, not eve y type of spatial metadata can be derived from GIS. Some of them have to be obtained by some exogenous processes. Regardless of the sources of spatial metadata, they should be stored as part of the spatial databases, and treated as decision aid to assist data users. The paper concludes with an example showing how spatial metadata can provide insight in identiJLing poor neighborhoods forfurtherpolicyfonnulation. C. Victor Wu Department 0; Geography Sam ford University Birmingham, AL 35229 lJ.S.A