In certain situations, there’s simply no way to display certain data objects on a graph that Prism generates. This is because the underlying structure of the graph is simply incompatible with those data objects. Currently, the only time that this occurs is when Prism generates a standalone dendrogram graph. This graph can only be created as part of the output of the hierarchical clustering analysis. If you open the Format Graph dialog on this type of graph and try to add any other type of data objects (symbols, connecting lines, confidence ellipses, convex hulls, or a heat map), you’ll be presented with the following error message:

“The [...] data object cannot be added to this graph.”

This is a clear, but not extremely explanatory message. The reason that these other data objects cannot be added to the standalone dendrogram graph is that the underlying structure of the graph is fundamentally unique for dendrograms in Prism when compared to other graph types. There’s simply no way to define where these data objects should be placed on the graph. The good news is that it’s very uncommon to see these other sorts of data objects added to a standalone dendrogram, so encountering this message should be terribly problematic. Note that adding dendrogram data objects to a heat map can be done in Prism, and is available as an optional graph output from the hierarchical clustering analysis.