The scales of human mobility
人类活动规模
▲ 作者：Laura Alessandretti, Ulf Aslak & Sune Lehmann
▲ 链接：
https://www.nature.com/articles/s41586-020-2909-1
▲ 摘要
当前人们对个人和集体流动模式的理解中有一个矛盾的核心。一方面，在大量经验数据集分析的驱动下，关于人类活动的高影响力文献发现，人类活动没有显示出特征性空间尺度的证据。人类活动性被描述为无尺度的。
另一方面，在地理上，尺度的概念（指从单个建筑到社区、城市、地区和国家的有意义的描述水平）是描述人类行为的各个方面的中心，比如社会经济互动，或者政治和文化动态。
研究组通过证明日常的人类活动确实包含有意义的尺度来解决这个明显的悖论，对应于限制活动行为的空间“容器”。无尺度的结果源于容器之间的总位移。
研究组提供了一个简单的模型，即通过给出一个人的轨迹，来推断出他们的邻居、城市等，以及这些地理容器的大小。研究组发现，用来描述70多万人轨迹的容器确实具有典型的规模。
研究组证明他们的模型也能够产生高度现实的轨迹，并提供了一种理解不同国家、性别群体和城乡地区之间流动行为差异的方法。
▲ Abstract
There is a contradiction at the heart of our current understanding of individual and collective mobility patterns. On the one hand, a highly influential body of literature on human mobility driven by analyses of massive empirical datasets finds that human movements show no evidence of characteristic spatial scales. There, human mobility is described as scale free. On the other hand, geographically, the concept of scale—referring to meaningful levels of description from individual buildings to neighbourhoods, cities, regions and countries—is central for the description of various aspects of human behaviour, such as socioeconomic interactions, or political and cultural dynamics. Here we resolve this apparent paradox by showing that day-to-day human mobility does indeed contain meaningful scales, corresponding to spatial ‘containers’ that restrict mobility behaviour. The scale-free results arise from aggregating displacements across containers. We present a simple model—which given a person’s trajectory—infers their neighbourhood, city and so on, as well as the sizes of these geographical containers. We find that the containers—characterizing the trajectories of more than 700,000 individuals—do indeed have typical sizes. We show that our model is also able to generate highly realistic trajectories and provides a way to understand the differences in mobility behaviour across countries, gender groups and urban–rural areas.