A Barber–Johnson diagram is a method of presenting hospital statistics combining four different variables in a unique graph, introduced in 1973.[1] The method constructs a scattergram where length of stay, turnover interval, discharges, and deaths per available bed are combined. These four variables have a common relationship between them and their combination in the diagram permitted a new improved way for analyzing efficiency and performance of the hospital sector. The most complete reference about how to construct the diagram could be found in Yates.[2] In this book, the appendix explains in detail the way for elaborating this kind of diagram.