A diagram that plots the sales of one variable against another, in order to ascertain how closely related the two products are. It appears as a collection of points ‘scattered’ on a graph, hence the name. By plotting correlation in the form of a graph, a business may be able to anticipate future sales or orders of a particular product or service by extrapolating the line of best fit between the two variables. When producing the graph, the independent variable (the assumed causal factor) is plotted on the X / horizontal axis. The dependent variable is plotted on the Y / vertical axis. A line of best fit is then drawn between the plotted points. The degree to which it is possible to draw a straight line through the points, demonstrates the extent of the correlation or the ‘closeness’ of the relationship between the two variables.