Using Anscombe's quartet plus one to illustrate data set matching, proper model specification, and relationships between inferential tests.

In 1854, London experienced an epidemic of cholera that took more than 500 lives. In September of that year, Dr. John Snow plotted the locations of cases and of water pumps throughout the city. Using simple graphical analysis, Dr. Snow quickly identified that the source of the epidemic was the Broad Street water pump. He had the handle removed, and the cholera breakout ended. While computational analysis might have resulted in the same solution set eventually, the proper visualization of the data provided a quick solution whichprobably saved lives (Tufte, 2002). Health professionals must therefore understand that graphical analysis of data is critical to the understanding of multidimensional relationships. The following discussion illustrates the importance of data visualization as applied to the field of healthcare. We begin with an examination F.J. Anscombe's and Edward Tufte's important works regarding graphical analysis.