Experience may provide the analyst with a good intuitive sense of how materials handling costs behave: the scattergraph then becomes a useful tool to quantify this intuition. Fitting a line to the points in this way is how the scatterplot method works. Keep in mind that the scattergraph and the other statistical aids are tools that help managers improve their judgment. Using the tools does not prevent the manager from using his or her own judgment to alter any of the estimates produced by formal methods.