Map to Geographic Information Systems (GIS) Maps as layers of geographic information Desire to ‘automate’ map Evolution of GIS –Create automated mapping systems –Analyze geographic relationships –Model real-world phenomena

What is GIS? Component definition: set of subsystems for the input, storage, transformation and retrieval of geographic data. Tool definition: measuring and analyzing aspects of geographic phenomena and processes. Model definition: a model of the real world.

GIS: It’s about Modeling and analyzing relationships and processes that occur across space, time and different scales. New tools for modeling –Geo-statistical procedures (Dead Crows) –Object-based GIS (Tiger model) –Seamless geographic databases (Big Apple)

Why spatial is special Modifiable area unit problem (MAUP) –Results of statistical analysis are sensitive to the zoning system used to report aggregated data –Results of statistical analysis are sensitive to the scale at which the analysis are performed –Must examine sensitivity of results to MAUP Boundary problem –Study areas are bounded and results just outside the study are can affect results. –Size and shape can affect results Migration –Rhode Island (xs) –Tennessee (xl) –Ohio (jr)

Why spatial is special (cont.) Spatial sampling –Space can be used as a means of stratification Spatial autocorrelation –Refers to the fact that values of a variable close in space are related Problems: Implication for sampling is that samples close in space may not be independent –Spatial autocorrelation can be calculated and variances can be adjusted accordingly Prospects: spatial autocorrelation can be used to estimate values at unknown locations based on surrounding know points (interpolation).

Why spatial is special (cont.) Data management –Editing Editing of spatial data is a long transaction –User needs to “check out” a region for extended periods of time –Other users need access Spatial databases are version managed to permit multiple long-transaction editing –Access Indexes are spatially based –Quad-tree recursive algorithm Addition of temporal dimension requires a second index. Optimization of spatial-temporal searching is still a topic under research