clustering

Examples of clustering in the following topics:

• Clustering tools

  • Tools>Cluster>Hierarchical proceeds by initially placing each case in its own cluster.
  • This results in clusters of increasing size that always enclose smaller clusters.
  • "farthest neighbor") computes similarities between the member of the new cluster that is least similar to each other case not in the cluster.
  • This file was then input to Tools>Cluster>Hierarchical.
  • The E-I index is often most helpful, as it measures the ratio of the numbers of ties within the clusters to ties between clusters.

• Three sampling methods (special topic)

  • Then we sample a fixed number of clusters and collect a simple random sample within each cluster.
  • This technique is similar to strati ed sampling in its process, except that there is no requirement in cluster sampling to sample from every cluster.
  • Also, unlike stratified sampling, cluster sampling is most helpful when there is a lot of case-to-case variability within a cluster but the clusters themselves don't look very different from one another.
  • However, cluster sampling seems like a very good idea.
  • In the bottom panel, cluster sampling was used, where data were binned into nine clusters, three of the clusters were randomly selected, and six cases were randomly sampled in each of these clusters.

• Cluster Structure

  • An organization has a cluster structure when it is composed of numerous, relatively independent business divisions and subsidiaries.
  • Another form of cluster structure is known as a business cluster.
  • Clusters are considered to increase the productivity with which companies can compete, both nationally and globally.
  • Clusters are also very important aspects of strategic management.
  • Good examples of business clusters include Silicon Valley and Hollywood.

• Clustering similarities or distances profiles

  • Cluster analysis is a natural method for exploring structural equivalence.
  • Tools>Similarities), save the result, and apply cluster analysis directly (i.e.
  • Tools>Cluster).
  • The second panel shows a rough character-mapped graphic of the clustering.
  • The measures of clustering adequacy in Tools>Cluster can provide additional guidance.

• Clustering

  • Figure 8.8 shows the output of Network>Cohesion>Clustering Coefficient as applied to the Knoke information network.
  • The "overall" graph clustering coefficient is simply the average of the densities of the neighborhoods of all of the actors.
  • In assessing the degree of clustering, it is usually wise to compare the cluster coefficient to the overall density.
  • Of these, only one is present -- so actor 6 is not highly clustered.
  • Actors 8 and 10 are embedded in highly clustered neighborhoods.

• Value Clusters

  • People from different backgrounds tend to have different value systems, which cluster together into a more or less consistent system.
  • Certain values may cluster together into a more or less consistent system.
  • Some sociologists are interested in better defining and measuring value clusters in different countries.
  • To do so, they have developed what is called the World Values Survey, a survey of questions given to people around the world and used to identify different clusters of values in different regions.
  • Their responses are aggregated and can be used to reveal regional value clusters, like those displayed in this map.

• Boranes: Boron-Hydrogen Compounds

  • The larger boranes all consist of boron clusters that are polyhedral, some of which exist as isomers.
  • For example, isomers of B20H26 are based on the fusion of two 10-atom clusters.
  • The names for the series of boranes are derived from this general scheme for the cluster geometries:
  • closo- (from the Greek for "cage") a closed complete cluster (e.g., icosahedral B12H122−)
  • reaction of a nido-borane with an alkyne to give a carborane cluster

• Lab 2: Sampling Experiment

  • The student will demonstrate the simple random, systematic, stratified, and cluster sampling techniques.
  • NOTE : The following section contains restaurants stratified by city into columns and grouped horizontally by entree cost (clusters).
  • Pick a cluster sample of restaurants from two cities.

• Optional Collaborative Classrom Exercise

  • Create a cluster sample by considering each state as a stratum (group).
  • By using simple random sampling, select states to be part of the cluster.
  • Then survey every U.S. congressman in the cluster.

• Clusters of Neuronal Cell Bodies

  • In neuroanatomy, a nucleus is a brain structure consisting of a relatively compact cluster of neurons.
  • In the peripheral nervous system, a cluster of neurons is called a ganglion.