I just attempted implementations of Ward linkage and UPGMA linkage, as well as Pearson and Euclid similarity coefficients. To my surprise, both similarity coefficients gave the same clustering with the Ward linkage. Should this be the case? Is this an indication that I made a mistake in my implementation?
I can tell you that, although the clustering was the same, the depth of the clusters were different. I can also tell that the similarity coefficients gave different clustering with the UPGMA linkage.