Ranking systems that account for the reputation of the users can be biased towards different demographic groups, especially when considering multiple sensitive attributes (e.g., gender and age). Providing guarantees of reputation independence can lead to unbiased and effective rankings. Moreover, these rankings are also robust to attacks. In a study, published by the Machine Learning …

Reputation-based ranking systems can be biased towards the sensitive attributes of the users, meaning that certain demographic groups have systematically lower reputation scores. Nevertheless, if we unbias the reputation scores considering one sensitive attribute, bias still occurs when considering different sensitive attributes. For this reason, reputation scores should be unbiased independently of any sensitive attribute …