Existing studies suggest distance decay as an important geographic property of online social networks. Namely, social interactions are more likely to occur among people who are closer in physical space. Limited effort has been devoted so far, however, to quantifying the impact of homophily forces on social network structures. In this study, we provide a quantitative understanding of the joint impact of geographic distance and people’s socioeconomic characteristics on their interaction patterns. By coupling large-scale mobile phone, income, and housing price data sets in Singapore, we reconstruct a spatially embedded social network that captures the cell phone communications of millions of phone users in the city. By associating phone users with their estimated residence, we introduce two indicators (communication intensity and friendship probability) to examine the cell phone interactions among places with various housing price values. Our findings suggest that, after controlling for distance, similar places tend to have relatively higher communication intensity than dissimilar ones, confirming a significant homophily effect as a determinant of communication intensity. When the analysis is focused on the formation of social ties, though, the homophily effect is more nuanced. It persists at relatively short distances, whereas at higher distances a tendency to form ties with people in the highest social classes prevails. Overall, the results reported in this study have implications for understanding social segregation in cities. In particular, the physical separation of social groups in a city (e.g., residential segregation) will have a direct impact on shaping communication or social network segregation. The study highlights the importance of incorporating socioeconomic data into the understanding of spatial social networks.

现有研究表明，距离衰减是在线社交网络的重要地理属性。也就是说，在物理空间较近的人之间更有可能发生社交互动。然而，迄今为止，我们在量化同质性力量对社会网络结构的影响方面所做的努力有限。在这项研究中，我们对地理距离和人们的社会经济特征对其互动模式的共同影响提供了定量理解。通过耦合新加坡的大规模手机、收入和房价数据集，我们重建了一个空间嵌入式社交网络，该社交网络捕捉了该市数百万电话用户的手机通信。通过将电话用户与他们的估计居住地相关联，我们引入了两个指标（通信强度和友谊概率）来检查不同房价值的地方之间的手机交互。我们的研究结果表明，在控制距离后，相似的地方往往比不同的地方具有相对更高的沟通强度，证实了显着的同质效应是沟通强度的决定因素。然而，当分析集中在社会纽带的形成上时，同质性效应会更加微妙。它在相对较短的距离内持续存在，而在较远的距离内，与最高社会阶层的人形成联系的趋势盛行。总体而言，本研究报告的结果对理解城市的社会隔离具有重要意义。特别是，城市中社会群体的物理分离（例如，居住隔离）将对塑造沟通或社交网络隔离产生直接影响。该研究强调了将社会经济数据纳入对空间社会网络的理解的重要性。