dendrogram node height

Question

In my lectures, we are told that the height of the node connecting two clusters in a dendrogram should be the distance between the clusters. However, on Wikipedia, it says that the height of the node should be half of the distance between the clusters. This is according to the Wikipedia article because of the ultrametric constraint $d(x,z) \leq max(d(x,y), d(y,z))$. I can't find any information online clarifying this.

Answer 1

It is traditional to make the height in a dendrogram equal to the (generalized) distance between clusters, but one can scale this height arbitrarily so long as the vertical axis is properly labeled.