How People Move Movements Between Municipalities

Movements between regions

Visualization and data analysis by Ulf Aslak and Peter Møllgaard.

Using the Movement Maps we can visualize the distribution of where people spend their days relative to their nights. While not accurate in every single case, it’s perhaps easier to say that we are able to see where people live (spend their nights) and work (spend their days). Or even more compactly, that we can look at commuting patterns over time.

This figure is interactive! You can:

  • Hover the curser over an administrative region to display the share of the Facebook population that makes daily journeys we assume represents work.
  • Click any administrative region to see where the population in that region goes to work.
  • Drag the time slider to display data for different dates.
  • Select either to display valus for the selected date (On date), the Baseline or the percentage deviation between these (Change).
  • Hold shift key after having selected (clicked) a region to display where people who work there live (as opposed to the default: where people who live there work).
  • Press the escape key to unselect a region.

Based on three daily time windows, the Movement Maps provide a “travel count” for some area i which is the number of active Facebook uses who spent the majority of the previous time window inside some other area j. As discussed in ‘Data > Movement Maps’, this choice of aggregation by Facebook implies that we cannot accurately assess the full amount of travel happening between and within regions.

As noted above, however, we can reliably quantify which share of the population spends the working hours away from home. Specifically, given the way travel is aggregated in the Movement Maps, travel counts into regions/tiles in the night hours (16–00 window) represents the number of people that spend the majority of their working hours (8—16) somewhere else. Thus, it’s not unreasonable to think of these travel counts as representing people commuting.

The map above looks at day-to-day between-municipality commuting patterns before and after the lockdown. By default the map displays Change, which is the percentage deviation between the size of the working population on the date selected with the slider, and the corresponding baseline (before lockdown). Clicking On date shows value for the date selected in the slider and Baseline for the corresponding baseline day. You can click any municipality to reveal where people who live there go to work (and reversely hold shift to reveal where people working there live).

A general pattern is that people who live in urban municipalities also work where they live, whereas people who live in municipalities next to more urbanized municipalities tend to work away from their home municipality.

When moving the slider through time it is clear that that the deviation—the change—between Baseline and On date decreases. This is the same pattern that we summarize in ‘Visualizations > Staying home’ and ‘Visualizations > Going out’.

Note: When clicking an administrative region, Change values displayed on other regions can be dramatically large. This is because, typically, only a small share of region populations work outside their home region, and because of the deviation calculation is as simple as (A - B) / B, they can blow up if B is small.