10 results on '"Chi, Guanghua"'
Search Results
2. Migration and Social Networks: New Insights from Novel Data
- Author
-
Chi, Guanghua
- Subjects
Information science ,big data ,digital trace data ,dynamic social network ,migration ,social network - Abstract
Migrants play a central role in the economy and society of most developing countries and are primary drivers of economic mobility among poor and rural households. The decision to migrate is one of the most important economic decisions an individual can make. On the one hand, social networks play a crucial role in influencing people's migration decision. On the other hand, as migrants adapt to a new environment, their social network evolves. My research seeks to shed light on the influence of social networks on migration, as well as the influence of migration on social networks. This dissertation answers three questions on migration and social networks using large-scale social network data: (1) What are the roles of migrants in connecting global social networks? (2) How do social networks affect people's decision to migrate? (3) How do migrants' social networks evolve over the migration process?In the first chapter, I explore in detail the relationship between international social ties and global migration. Social ties form the bedrock of the global economy and international political order. Yet prior empirical studies have been constrained by a lack of granular data on the interconnections between individuals. In this study, using several billion domestic and international Facebook friendships, I find that long-term migration accounts for roughly 83% of international ties on Facebook. By computing the average shortest path length in a social graph with and without migrants, I find that migrants effectively decrease the length of the average shortest path, and act as conduits for more shortest paths than non-migrants.The second chapter studies how social networks influence an individual’s decision to migrate. Two distinct mechanisms through which social networks provide utility to migrants are disambiguated: first, that networks provide migrants with access to information, for instance about jobs and conditions in the destination; and second, that networks act as a safety net for migrants by providing material or social support. I use a massive `digital trace' dataset to link the migration decisions of millions of individuals to the topological structure of their social networks. The main analysis indicates that the average migrant derives more utility from `interconnected’ networks that provide social support than from `extensive’ networks that efficiently transmit information.In the third chapter, I develop and validate a novel and general approach to detecting migration events in trace data. The most common `frequency-based' approach to inferring migration events often results in mis-classifications. The novel approach accurately classifies migrations, and also provides more granular insight into migration spells and types than what are captured in standard survey instruments.The fourth chapter examines how migrants' social networks change over the migration and settlement process based on the migration events and dates that were detected in the third chapter. I characterize changes in network structure before and after migration by observing the evolving social networks of a nation's worth of migrants. I find stark and systematic changes in this structure: within two months of migrating, migrants cease communication with nearly half of their former contacts in their place of origin; these `lost' relationships are almost exactly offset by the 55% increase in new connections with people in the destination. I also show that friendship persistence and loss is highly predictable: the social ties most likely to persist are those that have frequent communication.As a whole, the chapters in this dissertation develop methods and theories to understand the interaction between migration and social networks. It lays the groundwork for future researchers answering questions in migration and social networks using population-scale digital trace data.
- Published
- 2020
3. Understanding the effects of administrative boundary in sampling spatially embedded networks
- Author
-
Chi, Guanghua, Liu, Yu, Shi, Li, and Gao, Yong
- Published
- 2017
- Full Text
- View/download PDF
4. Social Sensing: A New Approach to Understanding Our Socioeconomic Environments
- Author
-
Liu, Yu, Liu, Xi, Gao, Song, Gong, Li, Kang, Chaogui, Zhi, Ye, Chi, Guanghua, and Shi, Li
- Published
- 2015
5. Geographical impacts on social networks from perspectives of space and place: an empirical study using mobile phone data
- Author
-
Shi, Li, Wu, Lun, Chi, Guanghua, and Liu, Yu
- Published
- 2016
- Full Text
- View/download PDF
6. A general approach to detecting migration events in digital trace data.
- Author
-
Chi, Guanghua, Lin, Fengyang, Chi, Guangqing, and Blumenstock, Joshua
- Subjects
- *
BIG data , *CELL phones , *SURVEYS , *METADATA , *EMPIRICAL research , *SOCIAL media , *QUANTITATIVE research - Abstract
Empirical research on migration has historically been fraught with measurement challenges. Recently, the increasing ubiquity of digital trace data—from mobile phones, social media, and related sources of 'big data'—has created new opportunities for the quantitative analysis of migration. However, most existing work relies on relatively ad hoc methods for inferring migration. Here, we develop and validate a novel and general approach to detecting migration events in trace data. We benchmark this method using two different trace datasets: four years of mobile phone metadata from a single country's monopoly operator, and three years of geo-tagged Twitter data. The novel measures more accurately reflect human understanding and evaluation of migration events, and further provide more granular insight into migration spells and types than what are captured in standard survey instruments. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
7. Ghost Cities Analysis Based on Positioning Data in China
- Author
-
Chi, Guanghua, Liu, Yu, Wu, Zhengwei, and Wu, Haishan
- Subjects
Social and Information Networks (cs.SI) ,FOS: Computer and information sciences ,Computer Science - Computers and Society ,Physics - Physics and Society ,Computers and Society (cs.CY) ,FOS: Physical sciences ,Computer Science - Social and Information Networks ,Physics and Society (physics.soc-ph) - Abstract
Real estate projects are developed excessively in China in this decade. Many new housing districts are built, but they far exceed the actual demand in some cities. These cities with a high housing vacancy rate are called ghost cities. The real situation of vacant housing areas in China has not been studied in previous research. This study, using Baidu positioning data, presents the spatial distribution of the vacant housing areas in China and classifies cities with a large vacant housing area as cities or tourism sites. To the best of our knowledge, it is the first time that we detected and analyzed the ghost cities in China at such fine scale. To understand the human dynamic in ghost cities, we select one city and one tourism sites as cases to analyze the features of human dynamics. This study illustrates the capability of big data in sensing our cities objectively and comprehensively., added references for Case Study; corrected typos; revised argument in Introduction; added a sentence to explain the second-tier and third tier cities in Result; added two sentences to introduce the background of the study in Conclusion; added two people in the Acknowledgements; added a coauthor for his contribution in designing the algorithms of home-work detection and migration calculation
- Published
- 2015
8. Uncovering regional characteristics from mobile phone data: A network science approach.
- Author
-
Chi, Guanghua, Thill, Jean‐Claude, Tong, Daoqin, Shi, Li, and Liu, Yu
- Subjects
- *
CELL phones , *VORONOI polygons , *NETWORK analysis (Communication) , *SOCIOECONOMICS , *BETWEENNESS relations (Mathematics) - Abstract
We introduce network science methods to uncover inherent characteristics of functional regions. An aggregate spatial interaction network is constructed based on a large mobile phone data set including 431 million mobile calls made by 10 million anonymous customers over one month and the geographic locations of the mobile base towers involved in each call. We use Thiessen polygons (termed 'cells') as the unit of analysis to approximate the service area of each mobile base tower. Major findings encompass the following three aspects. First, cells with high betweenness centrality are linearly distributed in space, which closely aligns with major transportation corridors. We find that this pattern can be explained by analysing the characteristics of calling activities on transportation networks. Second, we detect a two-level hierarchy of communities that correspond well to county and prefecture-level administrative unit boundaries. Lastly, almost every community identified at the two hierarchical levels contains a cell with high betweenness. These cells are located near the political and economic centres and play the role of hubs in the regional socio-economic system. This research demonstrates that networks built from mobile phone data provide new understandings of spatial interactions and regional structures. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
9. Human mobility patterns in different communities: a mobile phone data-based social network approach.
- Author
-
Shi, Li, Chi, Guanghua, Liu, Xi, and Liu, Yu
- Subjects
- *
SOCIAL network analysis , *KERNEL functions , *SOCIAL facts , *CELL phones , *ALGORITHMS - Abstract
Detecting intensely connected sub-networks, or communities, from social networks has attracted much attention in social network studies. The widespread use of location-awareness devices provides a novel data source for constructing spatially embedded networks and uncovering spatial features of different population groups. Using an empirical mobile phone data-set, this paper attempts to explore the spatial distributions and human mobility patterns, as well as the interrelationship between them, at the community level. Three spatial patterns of communities are identified with the community detection algorithm and kernel density map method: single-centred distribution, dual-centred distribution and zonal distribution. We find different movement characteristics of these three community types by analysing angle distribution of trajectories and radius of gyration of users. Furthermore, we analyse spatial and temporal travel patterns for the users in dual-centred communities. The results indicate that people’s commuting travel brings about spatial interaction between urban district and suburbs, and verify our hypothesis that the distance decay effect along with social phenomena such as the home–work separation contributes to the formation of different community distributions. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
10. Microestimates of wealth for all low- and middle-income countries.
- Author
-
Chi G, Fang H, Chatterjee S, and Blumenstock JE
- Abstract
Many critical policy decisions, from strategic investments to the allocation of humanitarian aid, rely on data about the geographic distribution of wealth and poverty. Yet many poverty maps are out of date or exist only at very coarse levels of granularity. Here we develop microestimates of the relative wealth and poverty of the populated surface of all 135 low- and middle-income countries (LMICs) at 2.4 km resolution. The estimates are built by applying machine-learning algorithms to vast and heterogeneous data from satellites, mobile phone networks, and topographic maps, as well as aggregated and deidentified connectivity data from Facebook. We train and calibrate the estimates using nationally representative household survey data from 56 LMICs and then validate their accuracy using four independent sources of household survey data from 18 countries. We also provide confidence intervals for each microestimate to facilitate responsible downstream use. These estimates are provided free for public use in the hope that they enable targeted policy response to the COVID-19 pandemic, provide the foundation for insights into the causes and consequences of economic development and growth, and promote responsible policymaking in support of sustainable development., Competing Interests: The authors declare no competing interest., (Copyright © 2022 the Author(s). Published by PNAS.)
- Published
- 2022
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.