Exam 20: Cluster Analysis

What are the steps in conducting cluster analysis (Figure 20.3 in the text)?

The parallel threshold method differs from the other two non- hierarchical clustering procedures in that the objects can later be reassigned to clusters to optimize an overall criterion.

When cluster analysis is also used for clustering variables to identify homogeneous groups, the units used for analysis are the variables, and the distance measures are computed for all pairs of variables.

is a clustering procedure where all objects start out in one giant cluster. Clusters are formed by dividing this cluster into smaller and smaller clusters.

Principal components are usually easier to interpret than the cluster components.

Which method allows the researcher to obtain information on cluster membership of cases if the number of clusters is specified?

Clustering should be done on samples of at least 300 or more.

The method uses information on all pairs of distances, not merely the minimum or maximum distances.

Most clustering methods are relatively complex procedures that are supported by an extensive body of statistical reasoning.

A(n) or tree graph is a graphical device for displaying clustering results. Vertical lines represent clusters that are joined together. The position of the line on the scale indicates the distances at which clusters were joined.

The is a nonhierarchical method that specifies several cluster centers at once. All objects within a pre- specified threshold value from the center are grouped together.

In non- hierarchical clustering, the F test is only descriptive. Because the cases or objects are systematically assigned to clusters to maximize differences on the clustering variables, the resulting probabilities should not be interpreted as testing the null hypothesis of no differences among clusters.

Nonhierarchical clustering is faster than hierarchical methods.

If cluster analysis is used as a general data reduction tool, subsequent multivariate analysis can be conducted on the clusters rather than on the individual observations.

A _ is a lower- triangle matrix containing pairwise distances between objects or cases.

In non- hierarchical clustering, plotting the ratio of total within- group variance to between- group variance against the number of clusters is useful if you are .

The method is based on the maximum distance or the furthest neighbor approach.

Measuring similarity in terms of distance between pairs of objects is the most common approach used in cluster analysis for grouping similar objects together.

The is a nonhierarchical method in which a cluster center is selected and all objects within a pre- specified threshold value from the center are grouped together.

is a class of techniques used to classify objects or cases into relatively homogeneous groups.