Comparing more than two observations

Cluster Analysis in R

Dmitriy Gorenshteyn

Lead Data Scientist, Memorial Sloan Kettering Cancer Center

The closest observation to a pair

	1	2	3
2	11.7
3	16.8	18.0
4	10.0	20.6	15.8

• Is 2 is closest to group 1,4?
• Is 3 is closest to group 1,4?

Linkage criteria: complete

	1	2	3
2	11.7
3	16.8	18.0
4	10.0	20.6	15.8

• Is 2 is closest to group 1,4?
  • max(D(2,1), D(2,4)) = 20.6
• Is 3 is closest to group 1,4?
  • max(D(3,1), D(3,4)) = 16.8

Hierarchical clustering

Complete Linkage: maximum distance between two sets

Grouping with linkage & distance

Grouping with linkage & distance

Grouping with linkage & distance

Grouping with linkage & distance

Grouping with linkage & distance

Grouping with linkage & distance

Grouping with linkage & distance

Grouping with linkage & distance

Grouping with linkage & distance

Grouping with linkage & distance

Linkage criteria

Complete Linkage: maximum distance between two sets

Single Linkage: minimum distance between two sets

Average Linkage: average distance between two sets

Let's practice!

Cluster Analysis in R