Anscombe's quartet of datasets with identical statistical properties but radically different shapes.

Anscombe's quartet comprises four datasets that have nearly identical simple statistical properties, yet appear very different when graphed.

The image on the right shows scatterplots of Anscombe's quartet, a set of four different pairs of variables created by Francis Anscombe.

He later became interested in statistical computing, and stressed that "a computer should make both calculations and graphs", and illustrated the importance of graphing data with four data sets now known as Anscombe's quartet.

Unfortunately, a high R (coefficient of determination) does not guarantee that the model fits the data well, because as Anscombe's quartet shows, a high R can occur in the presence of misspecification of the functional form of a relationship or in the presence of outliers that distort the true relationship.