Can We Predict the Election Outcome from Sampled Votes?

E. Micha, N. Shah
AAAI 2020
Abstract
In the standard model of voting, it is assumed that a voting rule observes the ranked preferences of each individual over a set of alternatives and makes a collective decision. In practice, however, not every individual votes. Is it possible to make a good collective decision for a group given the preferences of only a few of its members? We propose a framework in which we are given the ranked preferences of k out of n individuals sampled from a distribution, and the goal is to predict what a given voting rule would output if applied on the underlying preferences of all n individuals. We focus on the family of positional scoring rules, derive a strong negative result when the underlying preferences can be arbitrary, and discover interesting phenomena when they are generated from a known distribution.

Experiments:

Election type Culture Candidates Voters Instances Parameters
Ordinal Impartial Culture {5} {1000} 1000000 None
Ordinal Mallows {5} {1000} 1000000 $\phi = 1/3$