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The Visualisation of Area-based Spatial Data

4.4 SpaceStat

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4.4.1 Functionality

SpaceStat differs from the other packages reviewed here in that the package itself has no graphical facilities at all. However an extension to ArcView has recently been developed, which allows the results from SpaceStat to be visualised using the facilities of ArcView.
The focus of SpaceStat, as the name implies, is on spatial statistics and in particular, spatial econometric modelling. The ArcView extension provides facilities for viewing the original data through a map linked to one or more statistical graphs (boxplot, histogram, scatterplot). In addition, by importing a results file from SpaceStat, it is also possible to explore the smooth and rough elements of the spatial data using lagged boxplots and local autocorrelation coefficients.
In the time available it was not possible to run an analysis in SpaceStat and export the results to ArcView. The histogram and boxplot in ArcView were fine, but there is a minor problem in that if a graph is drawn, then clicking on any of the other windows (e.g. the map) causes the graph window to be minimised onto the Windows 95 task bar.

4.4.2 Ease of Use

The menu system of SpaceStat has a very old-fashioned feel to it compared with modern Windows-based systems. However, it is actually easy to use once the basic technique of entering command parameters has been mastered.
The documentation is extremely thorough, leading the user through a series of worked examples and explaining the principles underlying the methods which are available. Given the highly specialised nature of the statistical techniques which SpaceStat has been written to implement, there is no `quick-fix' solution to learning the package - anyone wishing to use it would simply have to devote some time to reading the manual carefully.

4.4.3 Implementation

SpaceStat comes on diskette, and installation is reasonably straightforward. One minor problem is that it requires a particular graphics device driver (ANSI.SYS) to be loaded, otherwise the menu system does not appear properly on screen. Installing ANSI.SYS is simply a matter of editing the CONFIG.SYS file - simple enough for the technically confident, but something of a deterrent for others, and not what one expects in the days of the Windows 95 Install Shield! As an extra complication, when SpaceStat was installed on a machine running Windows 95, it was not easy to find the ANSI.SYS driver and the help of our local computer service had to be enlisted! Data input is via text files, with the option of providing alternative weights matrices, either as text files or as output files from GIS packages such as ARC/INFO and IDRISI.

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