SENSITIVITY OF MEMBERSHIPS TO ATTRIBUTE VARIATION AROUND SELECTED CENTROIDS AND INTERGRADES IN THE CONTINUOUS AUSTRALIAN GREAT SOIL GROUPS CLASSIFICATION-SYSTEM

This paper deals with the sensitivity of classification, i.e. the exte nt to which the modification of soil properties influences the degree of membership in a fuzzy or continuous soil classification system. The sensitivity around the centroids of four Australian Great Soil Groups (GSG), black earth, red-brown earth, krasnozem and euchrozem was dete rmined for the 21 attributes that define the classes. In addition, pH, clay % and subsoil colour hue of two groups, krasnozem and euchrozem, were investigated. Each centroid has a particular sensitivity, almost completely different from the others and some attributes are crucial for identification of some soil classes. Although the classes were def ined by points in hyperspace they actually have a volume or hard core around the centroid where the membership is unity. In practical terms, membership sensitivity around centroids can be used for determining t he crucial attribute(s) for allocation to a given soil class and also for assessing the effect of missing data on soil identification and cl assification. Finally, our viewpoints switch from ideal or typical pro file to exemplar representation by using the sensitivity analysis.