Preferential Attachment and Fitness in the Evolution of the Brazilian Film Network

Abstract This study analyzes the network evolution, specifically that of the Brazilian film network. It examines two generative mechanisms that lie behind the network evolution: preferential attachment and fitness. The starting point is that preferential attachment and fitness may compete to shape the network evolution. We built a novel dataset with 974 Brazilian feature films released between 1995 and 2017 and used PAFit, a brand-new statistical method, to estimate the joint effects of preferential attachment and fitness on the evolution of the Brazilian film network. This study concludes that the network evolution is shaped by both preferential attachment and fitness. However, in the presence of fitness, the effects of preferential attachment on the network evolution become weaker. This means that the node ability to form ties in the Brazilian film network is mainly explained by its fitness. Besides, the preferential attachment assumes a sub-linear form. Costs, communication and managerial capabilities, and node age explain why nodes are unable to accumulate ties at rates proportional to their degree. Finally, preferential attachment and fitness manifest themselves heterogeneously, depending on either the type or the duration of the network. Preferential attachment drives the cast network evolution, whereas fitness is the main generative mechanism of the crew network. Actors and actresses rely on their status, privilege, and power to obtain future contracts (preferential attachment), whereas technical members are selected on the basis of their talent, skills, and knowledge (fitness). Due to node age or exit, preferential attachment becomes stronger in shorter networks.

摘要 本研究聚焦网络演化分析，尤以巴西电影网络为研究对象。本研究考察了驱动该网络演化的两类核心生成机制：偏好依附（preferential attachment）与适配度（fitness）。本研究的核心前提为：偏好依附与适配度可能在网络演化的塑造过程中相互竞争。我们构建了一套全新的数据集，涵盖1995年至2017年间上映的974部巴西剧情长片，并采用PAFit这一全新统计方法，估算偏好依附与适配度对巴西电影网络演化的联合影响。本研究得出结论：该网络的演化同时受偏好依附与适配度的共同塑造。然而，当适配度效应存在时，偏好依附对网络演化的影响会有所减弱。这意味着，在巴西电影网络中，节点建立联结的能力主要由其适配度所决定。此外，偏好依附呈现出亚线性形式。成本、沟通与管理能力，以及节点年龄，共同解释了为何节点无法按照与其度数成正比的速率积累联结。最后，偏好依附与适配度的作用表现存在异质性，具体取决于网络的类型或存续时长。偏好依附主导演员阵容网络的演化，而适配度则是幕后团队网络的核心生成机制。演员们依托自身地位、特权与影响力获取后续合作机会（偏好依附），而技术成员则基于其天赋、技能与专业知识被选中（适配度）。受节点年龄或退出效应影响，在存续时长更短的网络中，偏好依附的作用会更强。