About Connected Communities

This tool groups sub-national regions into "clusters" using the strength of Facebook friendship ties between them. Two regions are treated as close when a randomly chosen Facebook user in one is highly likely to be friends with a randomly chosen user in the other.

Under the hood it uses hierarchical clustering: every region starts on its own, and the communities whose residents are most connected are merged step by step until the number of clusters you chose remains. Merges are weighted by population, so communities reflect where people actually are rather than how finely a country happens to be subdivided. No geographic constraint is applied — clusters are usually contiguous, but a strong long-distance tie can place non-adjacent regions together.

The map shows the relative probability that a Facebook user in the selected location has a friendship link to a Facebook user in every other location at the same level.

The Social Connectedness Index is the number of Facebook friendship links between two locations divided by the product of their Facebook user populations, scaled so only relative values matter (e.g. if the SCI between location A and location B is twice as large as the SCI between location A and location C, then a randomly chosen Facebook user in location A is twice as likely to be friends with a randomly chosen Facebook user in location B than with a user in location C).

Black - German Folk land

= - Northern German culture

// - Southern German culture