In the Vector Analysis Toolbox of QGIS 3.2 next to "Distance Matrix" I stumbled upon "Distance to nearest hub (points)". I have no idea what a "hub" is in this context. Can someone give an explanation of the term "hub" as it is being used in QGIS?
A hub is an important node in a network. For example, an international airport is a hub for air flights. A large train station is a hub for rail.
In the context of QGIS it allows you to define some reference points (i.e. hubs) which you can measure the distance to with some of your other vector information.
For example this blog post measures the distance between bus stops (hubs) and buildings (other vector information).
The phenomenon of distance concentration, which is usually expressed as the ratio between some measure of spread (for example, standard deviation) and some the measure of magnitude (for example, the mean) of distances of all points in a data set to some arbitrary reference point or the point with high k-occurrences.