SAKWeb – Spatial autocorrelation and kriging web, a W3 geocomputation perspective

A thesis submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Information Systems

The present research focuses on the first software to offer spatial autocorrelation and association measures, spatial exploratory tools, variography and Ordinary Kriging (OK) in the World Wide Web. Exploiting IE®, ASP®, PHP® and IIS® capabilities, SAKWeb© version 2.0 was designed in an attractive and straightforward way for everyone’s use. Major commercial off-the-shelf spatial software is reviewed to confirm SAKWeb© improvements. As confirmed by Green and Bossomaier [2002], “it is essential for geographical studies to provide basic spatial autocorrelation indices and significance test computer programs for personal computers”. Spatial autocorrelation can provide an Exploratory Spatial Data Analysis (ESDA) tool for atypical locations, trends, transition regions and spatial patterns. The weight matrix (W) is assessed on the basis of the covariogram contiguity. In accordance with various distance ranges, SAKWeb© selects the one with the highest global Moran I to setup the conventional and the Moran location scatterplot. In addition, the Moran I correlogram may lead to a re-estimation process of the best variogram range, sill, model and nugget-effect factors. Some of the possibilities are dropping outliers, tracing patterns of quadrants I and III, highlighting transition samples or maintaining the original dataset. IDW is also stressed as a poor method for W specification. Nearest neighborhood analysis and brushing operations are added features for enhanced dataset familiarity.(...)