Small multiples technique consists of the same graphical design structure repeated several times (Tufte, 1983). It is used to compare at a glance series of graphics showing the same combination of variables while another variable changes. This method considers positioning similar graphical elements together in order to emphasise changes of the data. It's an effective way to reveal differences, or to shows tendencies and variations in time.
The figure illustrates a small multiples design for representing the coverage of mobile phones in Switzerland for the tree main operators. Comparisons are possible to decide which operator utilises on a specific region for best signal reception.