Figure 8
Histogram of lags in seasonal components. It shows the months needed (lag) to best align the incoming and outgoing traffic (i.e., to achieve the highest cross-correlation). The lag can be interpreted as giving an estimate of the average duration of the trip. Note that \(\mathrm{lags}\neq 0 \lor 6\) are ambiguous as long as the direction of travel is unknown because a stay of, say, 3 months of people from A in B equals a 9-month stay of people from B in A