The next step is to group the drugs hierarchically according to their similarity. To do so, first take the two drugs that are closest and draw a circle around them. Then, take the drug that is next closest to either of these first two and draw a curve that encloses all three (see Figure 2). Proceed until all drugs are included, giving a diagram depicting hierarchical clusters of decreasing similarity as shown in Figure 2. It is also possible to depict the drug similarities using a dendogram, where the length of the path in the diagram between two drugs reflects the similarity between the drugs (see Figure 3). Construct both.