Meaning of "data pooling"

What does "data pooling" actually mean?

The program Distance enables pooling of data across sites and derivation of density estimates at those sites (strata) where there are too few records to fit separate detection function.

A car pool is an arrangement where several people share use of their cars, often for regular trips to work/school/shopping. The idea being that with more people in each car, less cars are actually used in total, so it's largely a matter of efficiency.

In the more general case, we pool our resources so that collectively we make better use of them. In the computing sense, data pool can be slightly misleading, because it often just means a centralised database. Strictly speaking, it ought to mean an arrangement whereby multiple distributed data servers store "their own" data locally but provide access to that data across the entire network. In practice, it's a buzzword that's often used loosely.

Generally speaking, this is the same as "pooling your resources", i.e. combining all of your initlally-separate resources into a single large pool so as to enable larger efforts and results than anyone could have made individually.

So, 'pooling the data' means combining all of the data points from various sites into a single large collection so that you can run detection functions on the entire collection and calculate a density estimate, where if you had run the detection on a single site's data set, there would not have been enough data in the set to make a decent estimate.