Though algorithms promise many benefits including efficiency, objectivity and accuracy, they may also introduce or amplify biases. Here we study two well-known algorithms, namely PageRank and Who-to-Follow (WTF), and show under which circumstances their ranks produce inequality and inequity when applied to directed social networks. To this end, we propose a directed network model with preferential attachment and homophily (DPAH) and demonstrate the influence of network structure on the rank distributions of these algorithms. Our main findings suggest that (i) inequality is positively correlated with inequity, (ii) inequality is driven by the interplay between preferential attachment, homophily, node activity and edge density, and (iii) inequity is mainly driven by homophily. In particular, these two algorithms amplify, replicate and reduce inequity in top ranks when majorities are homophilic, neutral and heterophilic, respectively. Moreover, when inequity is amplified, minorities may improve their visibility in the rank by connecting strategically in the network. For instance, by increasing their homophily when majorities are also homophilic. These findings shed light on social and algorithmic mechanisms that hinder equality and equity in network-based ranking and recommendation algorithms.
翻译:虽然算法可以带来许多好处,包括效率、客观性和准确性,但它们也可能引入或扩大偏差。 在这里,我们研究两个众所周知的算法,即PageRank和Who-to-fo(WTF),并显示在哪些情况下,他们的排名产生不平等和不平等,适用于定向社会网络。为此目的,我们提出一个具有优先属性和同质(DPAH)的定向网络模式,并展示网络结构对这些算法的级别分布的影响。我们的主要调查结果表明:(一)不平等与不平等有正比关系,(二)不平等是由优先属性、同质、节活动和边际密度之间的相互作用所驱动的;(三)不平等主要由同质驱动的。特别是,这两种算法在多数为同性、中立性和异性的情况下,扩大、复制和减少高层的不平等。此外,如果不平等扩大,少数群体可以通过网络中的战略联系来提高其在排名中的知名度。例如,在主要属性也是同质主义的情况下,通过增加其同系性的活动和边际密度,从而增加了它们的同性。这些结论揭示了社会和算法等级,从而阻碍了平等和平等。