PVENN: Stata module to create proportional Venn diagram

pvenn produces proportioned and positioned Venn diagrams, supporting 2-circle and 3-circle Venn diagrams, as well as 1-circle diagram. pvenn can also draw a rectangle outside all circles to proportionally represent the total population size, when it is possible. Proportional Venn diagrams attempts to make each of the zones (the circles, the outside rectangle, and the set intersections) proportional to the population (value) assigned to the zone.