Cluster Analysis 2

Cluster Analysis 2 - Cluster Analyses Part 2 STA 4702/5701...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Cluster Analyses Part 2 STA 4702/5701 Spring 2009 1 Step 1. Choose the distance or similarity measure to be used in identifying clusters. We talked about some of the options last class. Step 2. Calculate the matrix of pair-wise distances or similarities between observations. Example: Suppose we have n = 4 observations, each with three variables { measured. We require a matrix of the pairwise Euclidean distances between observations. e.g. After calculating all pairwise distances we can construct a symmetric n × n matrix of the “similarities” between each pair: Obs. # 1 2 3 4 1 0 2.236 7.874 6.083 2 2.236 0 10.344 7.483 3 7.874 10.344 0 9.950 4 6.083 7.483 9.950 0 This matrix is now used to start our construction of clusters of observations. Step 3. Choose a clustering method. Clustering Methods A) Hierarchical Methods two types: Agglomerative Methods and Divisive Methods a. Agglomerative : start with each observation in its own cluster; compare similarities; if 2 observations are similar combine them into a single cluster; continue to group similar observations and clusters; stop clustering when all observations are combined into a single cluster b. Divisive : start with all observations in a single cluster; divide the cluster into two groups such that the variability within each new cluster is lower than the variability of the original cluster; continue until all observations are in their own cluster.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Cluster Analyses Part 2 STA 4702/5701 Spring 2009 2 Note that in hierarchical methods, the set of k
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/22/2011 for the course STA 4702 taught by Professor Staff during the Spring '08 term at University of Florida.

Page1 / 8

Cluster Analysis 2 - Cluster Analyses Part 2 STA 4702/5701...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online