Journal Article•
Exercise contagion in a global social network
TL;DR: Aral et al. as mentioned in this paper used exogenous variation in weather patterns across geographies to identify social contagion in exercise behaviors across a global social network and found that exercise is socially contagious and that its contagiousness varies with the relative activity of and gender relationships between friends.
Abstract: We leveraged exogenous variation in weather patterns across geographies to identify social contagion in exercise behaviours across a global social network. We estimated these contagion effects by combining daily global weather data, which creates exogenous variation in running among friends, with data on the network ties and daily exercise patterns of ∼1.1M individuals who ran over 350M km in a global social network over 5 years. Here we show that exercise is socially contagious and that its contagiousness varies with the relative activity of and gender relationships between friends. Less active runners influence more active runners, but not the reverse. Both men and women influence men, while only women influence other women. While the Embeddedness and Structural Diversity theories of social contagion explain the influence effects we observe, the Complex Contagion theory does not. These results suggest interventions that account for social contagion will spread behaviour change more effectively. Some argue that health-related behaviours, such as obesity, are contagious, but empirical evidence of health contagion remains inconclusive. Here, using a large scale quasi-experiment in a global network of runners, Aral and Nicolaides show that this type of contagion exists in fitness behaviours.
Citations
More filters
TL;DR: This survey reviews the approaches developed to reproduce various mobility patterns, with the main focus on recent developments, and organizes the subject by differentiating between individual and population mobility and also between short-range and long-range mobility.
635 citations
TL;DR: This review introduces recent progress in the study of coevolution spreading dynamics, emphasizing the contributions from the perspectives of statistical mechanics and network science.
192 citations
TL;DR: In this paper, a comprehensive and structured review of both traditional and frontier methods in learning causality and relations along with the connections between causal effects and machine learning is presented. But, the authors point out on a case-by-case basis how big data facilitates, complicates, or motivates each approach.
Abstract: This work considers the question of how convenient access to copious data impacts our ability to learn causal effects and relations. In what ways is learning causality in the era of big data different from -- or the same as -- the traditional one? To answer this question, this survey provides a comprehensive and structured review of both traditional and frontier methods in learning causality and relations along with the connections between causality and machine learning. This work points out on a case-by-case basis how big data facilitates, complicates, or motivates each approach.
185 citations
TL;DR: A simple analytical model calibrated with empirical estimates demonstrated that the “loss from anarchy” in uncoordinated state policies is increasing in the number of noncooperating states and the size of social and geographic spillovers.
Abstract: Social distancing is the core policy response to coronavirus disease 2019 (COVID-19). But, as federal, state and local governments begin opening businesses and relaxing shelter-in-place orders worldwide, we lack quantitative evidence on how policies in one region affect mobility and social distancing in other regions and the consequences of uncoordinated regional policies adopted in the presence of such spillovers. To investigate this concern, we combined daily, county-level data on shelter-in-place policies with movement data from over 27 million mobile devices, social network connections among over 220 million Facebook users, daily temperature and precipitation data from 62,000 weather stations, and county-level census data on population demographics to estimate the geographic and social network spillovers created by regional policies across the United States. Our analysis shows that the contact patterns of people in a given region are significantly influenced by the policies and behaviors of people in other, sometimes distant, regions. When just one-third of a state's social and geographic peer states adopt shelter-in-place policies, it creates a reduction in mobility equal to the state's own policy decisions. These spillovers are mediated by peer travel and distancing behaviors in those states. A simple analytical model calibrated with our empirical estimates demonstrated that the "loss from anarchy" in uncoordinated state policies is increasing in the number of noncooperating states and the size of social and geographic spillovers. These results suggest a substantial cost of uncoordinated government responses to COVID-19 when people, ideas, and media move across borders.
134 citations
TL;DR: A research agenda for measuring social media manipulation of elections is advocated, underutilized approaches to rigorous causal inference are highlighted, and the political, legal, and ethical implications of undertaking such analysis are discussed.
Abstract: Rigorous causal analysis could help harden democracy against future attacks To what extent are democratic elections vulnerable to social media manipulation? The fractured state of research and evidence on this most important question facing democracy is reflected in the range of disagreement among experts. Facebook chief executive officer Mark Zuckerberg has repeatedly called on the U.S. government to regulate election manipulation through social media. But we cannot manage what we do not measure. Without an organized research agenda that informs policy, democracies will remain vulnerable to foreign and domestic attacks. Thankfully, social media's effects are, in our view, eminently measurable. Here, we advocate a research agenda for measuring social media manipulation of elections, highlight underutilized approaches to rigorous causal inference, and discuss political, legal, and ethical implications of undertaking such analysis. Consideration of this research agenda illuminates the need to overcome important trade-offs for public and corporate policy—for example, between election integrity and privacy. We have promising research tools, but they have not been applied to election manipulation, mainly because of a lack of access to data and lack of cooperation from the platforms (driven in part by public policy and political constraints).
120 citations
References
More filters
TL;DR: A new method for estimation in linear models called the lasso, which minimizes the residual sum of squares subject to the sum of the absolute value of the coefficients being less than a constant, is proposed.
Abstract: SUMMARY We propose a new method for estimation in linear models. The 'lasso' minimizes the residual sum of squares subject to the sum of the absolute value of the coefficients being less than a constant. Because of the nature of this constraint it tends to produce some coefficients that are exactly 0 and hence gives interpretable models. Our simulation studies suggest that the lasso enjoys some of the favourable properties of both subset selection and ridge regression. It produces interpretable models like subset selection and exhibits the stability of ridge regression. There is also an interesting relationship with recent work in adaptive function estimation by Donoho and Johnstone. The lasso idea is quite general and can be applied in a variety of statistical models: extensions to generalized regression models and tree-based models are briefly described.
40,785 citations
TL;DR: A model based on these two ingredients reproduces the observed stationary scale-free distributions, which indicates that the development of large networks is governed by robust self-organizing phenomena that go beyond the particulars of the individual systems.
Abstract: Systems as diverse as genetic networks or the World Wide Web are best described as networks with complex topology. A common property of many large networks is that the vertex connectivities follow a scale-free power-law distribution. This feature was found to be a consequence of two generic mechanisms: (i) networks expand continuously by the addition of new vertices, and (ii) new vertices attach preferentially to sites that are already well connected. A model based on these two ingredients reproduces the observed stationary scale-free distributions, which indicates that the development of large networks is governed by robust self-organizing phenomena that go beyond the particulars of the individual systems.
33,771 citations
TL;DR: In this article, the authors pointed out that there is a strong functional tie between opinions and abilities in humans and that the ability evaluation of an individual can be expressed as a comparison of the performance of a particular ability with other abilities.
Abstract: Hypothesis I: There exists, in the human organism, a drive to evaluate his opinions and his abilities. While opinions and abilities may, at first glance, seem to be quite different things, there is a close functional tie between them. They act together in the manner in which they affect behavior. A person’s cognition (his opinions and beliefs) about the situation in which he exists and his appraisals of what he is capable of doing (his evaluation of his abilities) will together have bearing on his behavior. The holding of incorrect opinions and/or inaccurate appraisals of one’s abilities can be punishing or even fatal in many situations. It is necessary, before we proceed, to clarify the distinction between opinions and evaluations of abilities since at first glance it may seem that one’s evaluation of one’s own ability is an opinion about it. Abilities are of course manifested only through performance which is assumed to depend upon the particular ability. The clarity of the manifestation or performance can vary from instances where there is no clear ordering criterion of the ability to instances where the performance which reflects the ability can be clearly ordered. In the former case, the evaluation of the ability does function like other opinions which are not directly testable in “objective reality’. For example, a person’s evaluation of his ability to write poetry will depend to a large extent on the opinions which others have of his ability to write poetry. In cases where the criterion is unambiguous and can be clearly ordered, this furnishes an objective reality for the evaluation of one’s ability so that it depends less on the opinions of other persons and depends more on actual comparison of one’s performance with the performance of others. Thus, if a person evaluates his running ability, he will do so by comparing his time to run some distance with the times that other persons have taken. In the following pages, when we talk about evaluating an ability, we shall mean specifically the evaluation of that ability in situations where the performance is unambiguous and is known. Most situations in real life will, of course, present situations which are a mixture of opinion and ability evaluation. In a previous article (7) the author posited the existence of a drive to determine whether or not one’s opinions were “correct”. We are here stating that this same drive also produces behavior in people oriented toward obtaining an accurate appraisal of their abilities. The behavioral implication of the existence of such a drive is that we would expect to observe behaviour on the part of persons which enables them to ascertain whether or not their opinions are correct and also behavior which enables them accurately to evaluate their abilities. It is consequently
16,927 citations
TL;DR: In this article, the null hypothesis of no misspecification was used to show that an asymptotically efficient estimator must have zero covariance with its difference from a consistent but asymptonically inefficient estimator, and specification tests for a number of model specifications in econometrics.
Abstract: Using the result that under the null hypothesis of no misspecification an asymptotically efficient estimator must have zero asymptotic covariance with its difference from a consistent but asymptotically inefficient estimator, specification tests are devised for a number of model specifications in econometrics. Local power is calculated for small departures from the null hypothesis. An instrumental variable test as well as tests for a time series cross section model and the simultaneous equation model are presented. An empirical model provides evidence that unobserved individual factors are present which are not orthogonal to the included right-hand-side variable in a common econometric specification of an individual wage equation.
16,198 citations
TL;DR: The homophily principle as mentioned in this paper states that similarity breeds connection, and that people's personal networks are homogeneous with regard to many sociodemographic, behavioral, and intrapersonal characteristics.
Abstract: Similarity breeds connection. This principle—the homophily principle—structures network ties of every type, including marriage, friendship, work, advice, support, information transfer, exchange, comembership, and other types of relationship. The result is that people's personal networks are homogeneous with regard to many sociodemographic, behavioral, and intrapersonal characteristics. Homophily limits people's social worlds in a way that has powerful implications for the information they receive, the attitudes they form, and the interactions they experience. Homophily in race and ethnicity creates the strongest divides in our personal environments, with age, religion, education, occupation, and gender following in roughly that order. Geographic propinquity, families, organizations, and isomorphic positions in social systems all create contexts in which homophilous relations form. Ties between nonsimilar individuals also dissolve at a higher rate, which sets the stage for the formation of niches (localize...
15,738 citations