Social Group Identification and Clustering

Some methods for object group identification applicable for social group identification are compared. We suppose that people are characterized by their actions, for example the deputies are characterized by their voting habits. We are interested in binary data analysis (e.g. the result of voting is yes or not). The dataset consisting of the roll-call votes records in the Russian parliament in 2004 was analyzed. Methods of hierarchical and fuzzy clustering, and Boolean factor analysis are applied. In the first case, we propose two-step analysis in which factor loadings (as result of factor analysis of objects) obtained in the first step are interpreted by cluster analysis in the second step. For the cluster number determination both traditional and modified coefficients are used. Further, we suggest using Hopfield-like neural network based Boolean factor analysis for this purpose. This proposed method gives the best results in the case of deputies grouping.