The Swallow-Tail Plot: A Simple Graph For Visualizing Bivariate Data

We suggest a new plot for bivariate data based on the angular display of two standardized vectors. This graph shows at a glance the sign and the magnitude of the correlation and the possible univariate or bivariate outliers by means of the orientation of the axes and the shape of the tails. It may be useful as an alternative visual criterion that may be added to the traditional methods. Furthermore we propose the extension to more than two variables through a swallow-tail plot matrix.