Example 8.3.4 of the textbook uses hypothetical data to illustrate how the dot product can be used to discover the mode of action of novel biochemical compounds. This technique has been used with real data in a number of different contexts.
As an example, researchers quantified the genome expression profile of a particular kind of mutant yeast cell relative to normal cells (the BB material associated with Example 8.1.2 on this website explains how this type of expression profile is measured). They also then quantified the genome expression profile of yeast cells when they were subjected to different chemical compounds. The goal was to identify a chemical compound that mimicked the effect of the mutation. They did so by looking at the dot product of the expression profiles of the different compounds with that of the mutant.
References
Martin, M.J. et al. 1998. Drug target validation and identification of secondary drug target effects using DNA microarrays. Nature Medicine 4:1293-1301