I recommend reading this blog post from Jeffrey Veen, author of “The Art & Science of Web Design”.

You may be familiar with Dr John Snow as the man who successfully traced the source of London’s 1854 cholera outbreak. A pub on Broadwick Street in Soho is named after him, and the water-pump that started it all is preserved outside as a monument.

This post discusses the way the in which Dr Snow helped to ‘sell’ the results of his research, adapting an existing visualisation to create an overlaid map which communicated, in a far more immediate way than raw data or polemic might have done, the central thrust of his argument.

It’s an interesting and early example of how well-designed data visualisations can quickly convey information which could otherwise be comprehensible only to experts and adepts.