Tham khảo tài liệu 'data analysis machine learning and applications episode 1 part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 54 Kamila Migdaỉ Najman and Krzysztof Najman itself6. Since the learning algorithm of the SOM network is not deterministic in subsequent iterations it is possible to obtain a network with very weak discriminating properties. In such a situation the value of the Silhouette index in subsequent stages of variable reduction may not be monotone what would make the interpretation of obtained results substantially more difficult. At the end it is worth to note that for large databases the repetitive construction of the SOM networks may be time consuming and may require a large computing capacity of the computer equipment used. In the opinion of the authors the presented method proved its utility in numerous empirical studies and may be successfully applied in practice. References DEBOECK G. KOHONEN T. 1998 Visual explorations in finance with Self-Organizing Maps Springer-Verlag London. GNAnAdESIKAN R. KETTENRING . TSAO . 1995 Weighting and selection of variables for cluster analysis Journal of Classification vol. 12 p. 113-136. GORDON . 1999 Classification Chapman and Hall CRC London KOHONEN T. 1997 Self-Organizing Maps Springer Series in Information Sciences Springer-Verlag Berlin Heidelberg. MILLIGAN . COOPER . 1985 An examination of procedures for determining the number of clusters in data set. Psychometrika 50 2 p. 159-179. MILLIGAN . 1994 Issues in Applied Classification Selection of Variables to Cluster Classification Society of North America News Letter November Issue 37. MILLIGAN . 1996 Clustering validation Results and implications for applied analyses. In Phipps Arabie Lawrence Hubert G. DeSoete Eds. Clustering and classification River Edge NJ World Scientific p. 341-375. MIGDAE NAJMAN K. NAJMAN K. 2003 Zastosowanie sieci neuronowej typu SOM w badaniu przestrzennego zróznicowania powiatów Wiadomosci Statystyczne 4 2003 p. 72-85. ROUSSEEUW PJ. 1987 Silhouettes a graphical aid to the interpretation and validation of cluster analysis. J. .
