Displaying dendrograms

Hierarchical Clustering Schemes (HCS) are usually portrayed as a vertical stack, with each row representing a level of the HCS. The scheme is read top down, with the unclustered (“splitter”) level on the top, and the final single-cluster (“lumper”) level at the bottom of the scheme. Single points are denoted by a “.”, and clustered points are represented by  XXX joining them. Since each level is a single row, this representation emphasizes that the levels of the clustering form a simple ordering. It is sometimes referred to as a “line-printer” plot.

 

An HCS can also be represented as a horizontal  dendogram, read from left (splitter)  to right (lumper) but where the value of the dis/similarity measure (and not simply the level) at which points or clusters are merged is represented by the length of the branches. This representation thus encodes the quantitative information in the levels of the clustering, and not simply the order of them.

 

When the results of a HICLUS cluster analysis are displayed in the editor window, clicking on the Graphics button will show the cluster diagram (if any) following the current cursor position, as a graphic dendrogram. Alternatively, place the cursor within the boundaries of a selected line-printer plot and click on the Graphics button for this function.

Click on Save to save the current display in a file. Alternatively, you may use ALT+PrtScr to save the current display to the Clipboard for inclusion in other documents.

Click on Close to close the display and return to the main NewMDSX window.