Graphical Methods for Influential Data Points in Cluster Analysis

In cluster analysis, many numerical measures to detect which data points are influential have been proposed in the past literature. These numerical measures provide only limited information about which data points are influential but fail to reveal deeper relationships between the observations. They describe an overall pattern but fail to provide details about the mechanism that exists among the influential data points. In this paper, several graphical methods are described for detecting this mechanism. In the process, each data point is decomposed to show the pattern, how it influences other observations and the partitioning in cluster analysis. The approach also allows comparison of different clustering methods and how these options impact the relationship between observations.