The date used by social scientists are frequently multivariate. In part, this is a consequence of a need to characterise objects of interest, such as people, houses and so on, as fully as possible, but it is also often a result of a desire to capture concepts such as social class or intelligence and overcrowding that do not permit easy measurement along one axis of variation. In consequence, quantitative social science has a long history of using statistical and mathematical transforms of data matrices such as factor and principal component analysis to reduce the dimensionality of these data and perhaps suggest appropriate constructs that might also be used to describe individuals.These techniques are not intrinsically visual, although the reprojection of individual cases onto axes that define these constructs (for examples as component scores) may well create data that can be visualized by any of the standard techniques. There remains a need to develop appropriate alternative visualizations for multidimensional data that are efficient in allowing the detection of patterns in the multivariate data space. In this Case Study, Chris Brunsdon, Stweart Fotheringham and Martin Charlton develop and illustrate three alternative projections that can be applied to multivariate data.It is interresting to note that although the static displays produces are in themselves useful, they gain maximum utility when visualized in an interactive environment.
An Investigation of Methods for
AbstractAlthough visualisation has become a 'hot topic' in the social sciences, the majority of visualisation studies and techniques apply only to one or two dimensional datasets. Relatively little headway has been made into visualising higher dimensional data although, paradoxically, most social science datasets are highly multivariate. Investigating multivariate data, whether it be done visually or not, in just one or two dimensions can be highly misleading. Two well-known examples of this are the use of a correlation coefficient instead of a regression parameter as an indicator of the relationship between two variables and the use of scatterplots instead of leverage plots as indicators of relationships.This project has therefore investigated several methods for visualising aspects of higher dimensional (i.e. multivariate) datasets. Although some techniques are quite well-established for this purpose, such as Andrews Plots and Chernov Faces, we have ignored these because of their well-know problems. In the case of Andrews plots the functions used are subjective and the plots become very difficult to read when the number of observations rises beyond 30. In the case of Chernov faces, variables which are attached to certain attributes of the face, for example, the eyes, receive more weight in the subjective determination of 'unusual' cases.Instead we have examined the use of four newer techniques for visualising aspects of higher dimensional data sets: projection pursuit; Geographically Weighted Regression; RADVIZ; and Parallel Co-ordinates. In pr...