Anscombe's quartet - Wikipedia, the free encyclopedia

Anscombe's quartet - Wikipedia, the free encyclopedia: "Anscombe's quartet comprises four datasets which have identical simple statistical properties, yet which are revealed to be very different when inspected graphically. Each dataset consists of eleven (x,y) points. They were constructed in 1973 by the statistician F.J. Anscombe to demonstrate the importance of graphing data before analyzing it, and of the effect of outliers on the statistical properties of a dataset."