[postgis-users] Calculating variance of a set of points

[Aren Cambre]

I have a table with events. Each event happened at a listed reference marker
on a highway, and it also has latitude and longitude as recorded by an
observer of the event.

There are many events at each reference marker.

I want to check the precision of the latitude and longitude for events
recorded at each reference marker. Roughly, I would collect
all latitude/longitude points at each reference marker, then I would want to
see the average distance between each point and a centroid of all the
points.

How would I do that with PostGIS?

I understand how to convert latitude/longitude to a geometry type, but I am
not clear how to do the rest without iterating through each point
individually.

Aren
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