So now, as this blog is holistic, time to bring the last few notes together.
Pepper's Ghost is an illusion. According to the specifics of the patent, it documents the precise angle of semi-reflective surface needed to create the false image for various customer locations, although the term later developed a more generic usage. I had thought that it was a commonplace expression now, but I suppose that not everybody reads books about the history of magic and deception.
So in marketing, I refer to Pepper's Ghost as the illusion of 1 to 1 communication. It is a derivation of the original CRM vision, so it honours the creator, but the personal relationship required for message customisation does not exist - except in the mind of the customer. The personalisation is only an illusion. The customer only needs to "believe" that the marketing has been tailored to her.
To achieve this effect, we are back at the intersection of science, technology, psychology and statistics. That is the core of this site. And that is how mass marketing must work in the real world of incomplete information.