How to analyze the voting results?

Question

Mathematics

Good afternoon,
There are votings on the site, M users vote for N objects.
N - somewhere around 1000
M - somewhere around 30000
There are about 30-40 thousand votes per month.
Everyone can vote for one object only once (positively or negatively), according to the voting results, buns are distributed. There is a suspicion that users form tacit agreements and organize themselves into clans that vote positively for their own and negatively for others.
How can statistics be used to test this theory?

Answer 1

First, we need to define the feature space. What does it mean that the object is "own" or "foreign". well, then you can start with splitting into clusters and analyzing the resulting classifiers.