Anthony P. M. Coxon and Joachim Harloff published an german/english paper about sorting investigations:
“Classification is essential for human life. It enables the individuum to orient himself. Sorting is a natural way to classify. This presentation aims at presenting basic knowledge, or at least sources of knowledge about sorting as a method of research and design. Since a monograph on sorting already is at hand (Coxon, 1999), this paper does not fully cover and discuss the subject in depth. It is intended to show the basic ideas behind, resources available and actions to be taken for research. The chapters follow the natural steps of research, from a decision to make use of the sorting method to data analysis. Sorting results can be denoted in a number of ways, like cluster lists, lists of group members, dendrograms or general graphs, Venn diagrams and others (Coxon, 1999). Mathematically speaking, these different representations are at least partially equivalent. Some of these representations like trees and Venn diagrams can be used for data collection as well as for data analysis. Analysis of sorting results most often means no more than transforming data from one representation to another. From this point of view, sorting is just another application of graph theory, set theory and combinatorics.
Sorting is a convenient way to evaluate how people organise a set of perceptions, of objects or concepts. In a special case, these items may be connected by a “is a” or a “part of” relationship. Then, study participants may build groups of items, groups of groups and so on. More generally, items may be connected to each other in multiple ways, building a network of relationships. There may be more than one way to organise items depending on the criteria used for sorting and personal opinion.
Partitions, fuzzy sets, cover sets, trees and networks are models of human cognition and memory supported by the sorting method. The cognitive structure is assumed to remain stable at least for the time period from the beginning of the evaluation to the implementation of results (e.g., of a web site by visitors whose model of the site had been investigated).”
