A schematic representation of one user’s mobility trajectory and the resulting inter-observation times. On the left, the mobility trajectory of one person is visualized both as a spatial representation (top) and as a timeline (bottom). In the spatial representation each circle corresponds to a city, and an arrow corresponds to a movement from one city to another. The ordering of the movements is indicated by ordinal numbers and the times when the user has been observed in each city are shown below the name of each city. The timeline presentation below shows the same information in a more compact form. On the right, we have also listed all inter-observation times that can be computed from the trajectory.