Achieving Fully Proportional Representation Is Easy in Practice

P. Skowron, P. Faliszewski, A. Slinko
AAMAS 2013
Abstract
We provide experimental evaluation of a number of known and new algorithms for approximate computation of Monroe's and Chamberlin-Courant's rules. Our experiments, conducted both on real-life preference-aggregation data and on synthetic data, show that even very simple and fast algorithms can in many cases find near-perfect solutions. Our results confirm and complement very recent theoretical analysis of Skowron et al., who have shown good lower bounds on the quality of (some of) the algorithms that we study.

Remarks: There is a journal version: Piotr Skowron, Piotr Faliszewski, Arkadii M. Slinko: Achieving fully proportional representation: Approximability results. Artif. Intell. 222: 67-103 (2015)

Experiments:

Election type Culture Candidates Voters Instances Parameters
Ordinal Impartial Culture {10} {100} 500 None
Ordinal Impartial Culture {6} {9} 500 None
Ordinal Mallows Mixture {10} {100} 500 Mixture of 5 Mallows models, whose dispersion parameters and central orders are selected uniformly at random. Mixing probabilities are selected uniformly at random as well.
Ordinal Mallows Mixture {6} {9} 500 Mixture of 5 Mallows models, whose dispersion parameters and central orders are selected uniformly at random. Mixing probabilities are selected uniformly at random as well.
Ordinal PrefLib {10} {100} 500 https://www.preflib.org/dataset/00014
Ordinal PrefLib {6} {9} 500 https://www.preflib.org/dataset/00014
Ordinal PrefLib None None None https://www.preflib.org/dataset/00009
Ordinal PrefLib None None None https://www.preflib.org/dataset/00009
Ordinal PrefLib None None None https://www.preflib.org/dataset/00004
Ordinal PrefLib None None None https://www.preflib.org/dataset/00004
Ordinal Urn Model {10} {100} 500 {0.05}
Ordinal Urn Model {6} {9} 500 {0.05}
Ordinal Impartial Culture {10, 100} [1000-10000] 50 None
Ordinal Mallows Mixture {10, 100} [1000-10000] 50 Mixture of 5 Mallows models, whose dispersion parameters and central orders are selected uniformly at random. Mixing probabilities are selected uniformly at random as well.
Ordinal PrefLib {10, 100} [1000-10000] 50 https://www.preflib.org/dataset/00014
Ordinal PrefLib None None None https://www.preflib.org/dataset/00004
Ordinal Urn Model {10, 100} [1000-10000] 50 {0.05}
Ordinal PrefLib [30-300] {1000} 50 https://www.preflib.org/dataset/00004
Ordinal Urn Model [30-300] {1000} 50 {0.05}
Ordinal PrefLib {10, 30} [50-400] 50 https://www.preflib.org/dataset/00014
Ordinal PrefLib None None None https://www.preflib.org/dataset/00004
Ordinal Urn Model {10, 30} [50-400] 50 {0.05}
Ordinal PrefLib {100} {1000} None https://www.preflib.org/dataset/00004