Hierarchical Clustering (Hierarchical Cluster Analysis or HCA) is a method of clustering which seeks to build a hierarchy of clusters
Hierarchical Clustering - Types
- Agglomerative Clustering: This is a “bottom-up” approach: each observation starts in its own cluster, and pairs of clusters are merged as one moves up the hierarchy
- Divisive Clustering: This is a “top-down” approach: all observations start in one cluster, and splits are performed recursively as one moves down the hierarchy