# Measuring the distance between data points based on mutual linkages

How to measure the distance between two data points (or: nodes?) based on their mutual share of linkages?

I don't know the technical term for that, so here is a fictitious example from scientific publishing:

• Say that 20% of all citations from the journal Acta Mathematica go to the journal Nature.

• Only 5% of all citations from Acta Mathematica go to the Romanian Journal of Physics.

• On the other hand, Nature never cites Acta Mathematica, ...

• ... while 10% of the Romanian Journal of Physics' citations go to Acta Mathematica.

citing cited share
Acta Mathematica Nature 15%
Acta Mathematica Romanian Journal of Physics 8%
Nature Acta Mathematica 0%
Romanian Journal of Physics Acta Mathematica 10%

Given such inter-linkages, the Romanian Journal of Physics and Acta Mathematica are "closer" to each other than the Romanian Journal of Physics and Nature.

Is there a conventional way to calculate such distances?

I believe it would be too simplistic and wrong to just sum the mutual shares? I mean in the form of:

journal1 journal2 sum(share)
Acta Mathematica Romanian Journal of Physics 18%
Acta Mathematica Nature 15%

This seems too un-sophisticated and counterintuitive. If Acta Mathematica's citations to Nature would amount to 20%, then Nature would be "closer" to Acta Mathematica than the Romanian Journal of Physics is? This doesn't sound right to me.

I would be grateful for any hints regarding algorithms that would "objectively" measure such distances!

• This is definitely a graph problem. There are certainly many methods for calculating distances in a weighted graph, as well as clustering methods to group nodes together. There might also be a probabilistic angle to it. Commented Nov 27, 2021 at 16:29