A visual way of presenting data which might otherwise be offered in numerical form. It consists of the plotting of units as dots against an X and a Y axis representing two attributes, so that relationships between attributes as well as relationships between units may be shown. When clustering of dots into different groups occurs, it may suggest the presence of different classes. It is also possible to see whether one attribute co-varies with another, seen by the grouping of the dots around the line from bottom left to top right of the diagram.