David Lazer

David Lazer
Northeastern University | NEU

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Research items (174)
Conference Paper
Autocomplete algorithms, by design, steer inquiry. When a user provides a root input, such as a search query, these algorithms dynamically retrieve, curate, and present a list of related inputs, such as search suggestions. Although ubiquitous in online platforms, a lack of research addressing the ephemerality of their outputs and the opacity of the...
Conference Paper
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(NOTE: This is a peer-reviewed, terminal publication.) Using both survey- and platform-based measures of support, we study how polarization manifests for 4,313 of President Donald Trump’s tweets since he was inaugurated in 2017. We find high levels of polarization in response to Trump’s tweets. However, after controlling for mean differences, we s...
Article
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Machines powered by artificial intelligence increasingly mediate our social, cultural, economic and political interactions. Understanding the behaviour of artificial intelligence systems is essential to our ability to control their actions, reap their benefits and minimize their harms. Here we argue that this necessitates a broad scientific researc...
Article
The spread of fake news on social media became a public concern in the United States after the 2016 presidential election. We examined exposure to and sharing of fake news by registered voters on Twitter and found that engagement with fake news sources was extremely concentrated. Only 1% of individuals accounted for 80% of fake news source exposure...
Article
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There is a growing consensus that online platforms have a systematic influence on the democratic process. However, research beyond social media is limited. In this paper, we report the results of a mixed-methods algorithm audit of partisan audience bias and personalization within Google Search. Following Donald Trump's inauguration, we recruited 18...
Article
The present work proposes social media as a tool to understand the relationship between journalists’ social networks and the content they produce. Specifically, we ask, “what is the association between the partisan nature of the accounts journalists follow on Twitter and the news content they produce?” Using standard text scaling techniques, we ana...
Article
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People influence each other when they interact to solve problems. Such social influence introduces both benefits (higher average solution quality due to exploitation of existing answers through social learning) and costs (lower maximum solution quality due to a reduction in individual exploration for novel answers) relative to independent problem s...
Conference Paper
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Search engines are a primary means through which people obtain information in today's connected world. Yet, apart from the search engine companies themselves, little is known about how their algorithms filter, rank, and present the web to users. This question is especially pertinent with respect to political queries, given growing concerns about fi...
Article
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Most models of product adoption predict S-shaped adoption curves. Here we report results from two country-scale experiments in which we findlinearadoption curves. We show evidence that the observed linear pattern is the result of active information-seeking behaviour: individuals actively pulling information from several central sources facilitated...
Article
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A recent series of experiments demonstrated that introducing ranking bias to election-related search engine results can have a strong and undetectable influence on the preferences of undecided voters. This phenomenon, called the Search Engine Manipulation Effect (SEME), exerts influence largely through order effects that are enhanced in a digital c...
Article
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We examine the social antecedents of contributing to campaigns, with a particular focus on the role of population density and social networking opportunities. Using 10 years of US campaign contribution data from the Federal Election Commission and a national survey of party leaders, we find that recruiting contributors is easier in a densely popula...
Article
Social life increasingly occurs in digital environments and continues to be mediated by digital systems. Big data represents the data being generated by the digitization of social life, which we break down into three domains: digital life, digital traces, and digitalized life. We argue that there is enormous potential in using big data to study a v...
Article
The present work proposes the use of social media as a tool for better understanding the relationship between a journalists' social network and the content they produce. Specifically, we ask: what is the relationship between the ideological leaning of a journalist's social network on Twitter and the news content he or she produces? Using a novel da...
Article
Full-text available
Web search is an integral part of our daily lives. Recently, there has been a trend of personalization in Web search, where different users receive different results for the same search query. The increasing level of personalization is leading to concerns about Filter Bubble effects, where certain users are simply unable to access information that...
Article
This study reports the results of a multiyear program to predict direct executive elections in a variety of countries from globally pooled data. We developed prediction models by means of an election data set covering 86 countries and more than 500 elections, and a separate data set with extensive polling data from 146 election rounds. We also part...
Conference Paper
Manual annotations are a prerequisite for many applications of machine learning. However, weaknesses in the annotation process itself are easy to overlook. In particular, scholars often choose what information to give to annotators without examining these decisions empirically. For subjective tasks such as sentiment analysis, sarcasm, and stance de...
Article
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Experimental research in traditional laboratories comes at a significant logistic and financial cost while drawing data from demographically narrow populations. The growth of online methods of research has resulted in effective means for social psychologists to collect large-scale survey-based data in a cost-effective and timely manner. However, th...
Article
There have been serious efforts over the past 40 years to use newspaper articles to create global-scale databases of events occurring in every corner of the world, to help understand and shape responses to global problems. Although most have been limited by the technology of the time ( 1 ) [see supplementary materials (SM)], two recent groundbreaki...
Conference Paper
Currently, the de facto representational choice for networks is graphs which capture pairwise relationships between entities. This dyadic approach fails to adequate capture the array of group relationships that are more than the sum of their parts and prevalent in real-world situations. For example, collaborative teams, wireless broadcast, and poli...
Conference Paper
New information technologies are changing the way science is done. Programs like Zooniverse, Fold.It, and SciStarter demonstrate the power of recruiting online volunteers as participants and contributors to research. Platforms like Project Implicit and Volunteer Science confirm that a wide range of social scientific research can be conducted with v...
Conference Paper
In this workshop we will host presentations from researchers performing online experiments and spend a half day helping attendees create experiments using the Volunteer Science platform. Current approaches to online science use new information technologies to collect and processes data and engage citizen scientists across the globe. Programs like Z...
Conference Paper
"Man is by nature a political animal", as asserted by Aristotle. This political nature manifests itself in the data we produce and the traces we leave online. In this tutorial, we address a number of fundamental issues regarding mining of political data: What types of data could be considered political? What can we learn from such data? Can we use...
Conference Paper
To cope with the immense amount of content on the web, search engines often use complex algorithms to personalize search results for individual users. However, personalization of search results has led to worries about the Filter Bubble Effect, where the personalization algorithm decides that some useful information is irrelevant to the user, and t...
Article
There is an ever expanding body of work that considers how, when, and to what extent different forms and types of brokerage matter. However, surprisingly little is known why brokerage roles remain unfilled or how one becomes a broker in the first place. In a 2004 AJS paper Burt highlights half of the “who becomes a broker” equation, arguing that in...
Article
The use of socio-technical data to predict elections is a growing research area. We argue that election prediction research suffers from under-specified theoretical models that do not properly distinguish between ‘poll-like’ and ‘prediction market-like’ mechanisms understand findings. More specifically, we argue that, in systems with strong norms a...
Article
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The increasing abundance of digital textual archives provides an opportunity for understanding human social systems. Yet the literature has not adequately considered the disparate social processes by which texts are produced. Drawing on communication theory, we identify three common processes by which documents might be detectably similar in their...
Article
Do formal deliberative events influence larger patterns of political discussion and public opinion? Critics argue that only a tiny number of people can participate in any given gathering and that deliberation may not remedy—and may in fact exacerbate—inequalities. We assess these criticisms with an experimental design merging a formal deliberative...
Article
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Can data from mobile phones be used to observe economic shocks and their consequences at multiple scales? Here we present novel methods to detect mass layoffs, identify individuals affected by them and predict changes in aggregate unemployment rates using call detail records (CDRs) from mobile phones. Using the closure of a large manufacturing plan...
Article
Humanity is in the early stages of the rise of social algorithms: programs that size us up, evaluate what we want, and provide a customized experience. This quiet but epic paradigm shift is fraught with social and policy implications. The evolution of Google exemplifies this shift. It began as a simple deterministic ranking system based on the link...
Article
Using data from a novel laboratory experiment on complex problem solving in which we varied the structure of 16-person networks, we investigate how an organization’s network structure shapes performance of problem-solving tasks. Problem solving, we argue, involves both exploration for information and exploration for solutions. Our results show that...
Conference Paper
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The recent emergence of computational social science research methods has enabled us to conduct large­scale, population level experimentation that allow us to estimate causal effects of different policy alternatives. This new experimental paradigm is particularly suited to study patterns of social influence over real­world networks in which social...
Conference Paper
The recent emergence of computational social science research methods has enabled us to conduct large­scale, population level experimentation that allow us to estimate causal effects of different policy alternatives. This new experimental paradigm is particularly suited to study patterns of social influence over real­world networks in which social...
Article
Full-text available
This article advocates a lesson plan for introductory comparative politics and elections courses. The authors argue that Wikipedia (yes, Wikipedia) provides a unique platform for improving learning outcomes and a useful social good from traditional student papers on elections. The proposed lesson plan can achieve this in at least three ways: (1) by...
Article
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Do leaders persuade? Social scientists have long studied the relationship between elite behavior and mass opinion. However, there is surprisingly little evidence regarding direct persuasion by leaders. Here we show that political leaders can persuade their constituents directly on three dimensions: substantive attitudes regarding policy issues, att...
Article
We examine the social antecedents for contributing to campaigns, with a particular focus on the role of population density. Using 10 years of US campaign contribution data from the Federal Election Commission (FEC), we find that the idea of contributing to a campaign is easier to spread in a densely populated region, where the daily opportunity of...
Article
Full-text available
Search is a ubiquitous property of life. Although diverse domains have worked on search problems largely in isolation, recent trends across disciplines indicate that the formal properties of these problems share similar structures and, often, similar solutions. Moreover, internal search (e.g., memory search) shows similar characteristics to externa...
Article
Today, many e-commerce websites personalize their content, including Netflix (movie recommendations), Amazon (product suggestions), and Yelp (business reviews). In many cases, personalization provides advantages for users: for example, when a user searches for an ambiguous query such as ``router,'' Amazon may be able to suggest the woodworking tool...
Article
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The aim of this symposium is to move toward an agenda for future organizational research using digital network data, focusing on the key characteristics of digital data: scope, granularity and longitudinality. While much has already been accomplished in legitimizing the use of digital data in organizational network research, the potential for elect...
Article
Using data from a large laboratory experiment on problem solving in which we varied the structure of 16-person networks we investigate how an organization’s network structure may be constructed to optimize performance in complex problem- solving tasks. Problem solving involves both search for information and search for theories to make sense of tha...
Article
In many social contexts, individuals choose a set of social interactions to maximize their private benefit, but the resulting social network structure is a public phenomenon that affects all members of the network. This paper builds on previous research (Lazer and Friedman 2007), which found that under certain circumstances efficient collaborative...
Article
Developing technologies that support collaboration requires understanding how knowledge and expertise are shared and distributed among community members. We explore two forms of knowledge distribution structures, coordination and cooperation, that are central to successful collaboration. We propose a novel method for detecting the coordination of s...
Article
We thank Broniatowski, Paul, and Dredze for giving us the opportunity to reemphasize the potential of big data and make the more obvious point that not all big data projects have the problems currently plaguing Google Flu Trends (GFT), nor are these problems inherent to the field in general. Our
Article
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Research on human social interactions has traditionally relied on self-reports. Despite their widespread use, self-reported accounts of behaviour are prone to biases and necessarily reduce the range of behaviours, and the number of subjects, that may be studied simultaneously. The development of ever smaller sensors makes it possible to study group...
Article
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In recent years, the amount of information collected about human beings has increased dramatically. This development has been partially driven by individuals posting and storing data about themselves and friends using online social networks or collecting their data for self-tracking purposes (quantified-self movement). Across the sciences, research...
Article
Large errors in flu prediction were largely avoidable, which offers lessons for the use of big data.
Article
In response to its poor performance during the 2012-2013 flu season, Google Flu Trends (GFT) engineers announced a redesign of the GFT algorithm. Two changes were made: (1) dampening anomalous media spikes and (2) using ElasticNet, rather than regression, for estimation. This paper identifies several problems that persist in the new algorithm. Firs...
Conference Paper
The Hollywood Blacklist was based on a series of interviews conducted by the House Committee on Un-American Activities (HUAC), trying to identify members of the communist party. We use various NLP algorithms in order to automatically analyze a large corpus of interview transcripts and construct a network of the industry members and their “naming” r...
Article
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This paper develops a methodology to aggregate signals in a network regarding some hidden state of the world. We argue that focusing on edges around hubs will under certain circumstances amplify the faint signals disseminating in a network, allowing for more efficient detection of that hidden state. We apply this method to detecting emergencies in...
Article
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"Media events" such as political debates generate conditions of shared attention as many users simultaneously tune in with the dual screens of broadcast and social media to view and participate. Are collective patterns of user behavior under conditions of shared attention distinct from other "bursts" of activity like breaking news events? Using dat...
Article
Social media, like Twitter, have been widely used for exchanging information, opinions and emotions about events happening across the world. The authors introduce a new visualization tool for tracing the process of information diffusion on social media in real time. The design highlights the social, spatiotemporal processes of diffusion based on a...
Conference Paper
Social media have been employed to assess public opinions on events, markets, and policies. Most current work focuses on either developing aggregated measures or opinion extraction methods like sentiment analysis. These approaches suffer from unpredictable turnover in the participants and the information they react to, making it difficult to distin...
Conference Paper
Web search is an integral part of our daily lives. Recently, there has been a trend of personalization in Web search, where different users receive different results for the same search query. The increasing personalization is leading to concerns about Filter Bubble effects, where certain users are simply unable to access information that the searc...
Conference Paper
In this paper we discuss the analysis of mobile networks communication patterns in the presence of some anomalous "real world event". We argue that given limited analysis resources (namely, limited number of network edges we can analyze), it is best to select edges that are located around 'hubs' in the network, resulting in an improved ability to d...
Article
Full-text available
Legislative websites are increasingly important in the practice of representation. Since adapting old practices to new technology entails uncertainty, the authors expect legislative offices to learn website representation practices from each other. Using data from the 2006 and 2007 official home pages of members of the U.S. House of Representatives...
Article
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We examine the growth, survival, and context of 256 novel hashtags during the 2012 U.S. presidential debates. Our analysis reveals the trajectories of hashtag use fall into two distinct classes: "winners" that emerge more quickly and are sustained for longer periods of time than other "also-rans" hashtags. We propose a "conversational vibrancy" fra...
Conference Paper
In this interactive poster, we describe a system we designed for identifying and tracking the behavior of distinct audiences in social media streams.
Conference Paper
Politics is, in part, an intrinsically relational phenomenon. The central construct of politics is power-but power is not an attribute, it's a relationship, where person A can influence person B, group X has power over group Y, and so on. In part because of the rise of network science, political science has devoted increasing attention to the netwo...
Chapter
In Chapter 9, political scientist and scholar of social networks David Lazer gives an overview of the standard tools of social network analysis. He explains how network dynamics can be useful for understanding human rights issues as they relate to global flows of people, information and goods, as well as for understanding the relationships between...
Article
This paper introduces the concept of semantic organizing processes as a means of inferring theoretically meaningful behavior from the observation of raw text. Semantic organizing processes are mechanisms by which a set of authors come to produce texts that are similar in some observable, quantifiable way. We introduce three broad semantic organizin...
Article
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When and where is an idea dispersed? Social media, like Twitter, has been increasingly used for exchanging information, opinions and emotions about events that are happening across the world. Here we propose a novel visualization design, “Whisper”, for tracing the process of information diffusion in social media in real time. Our design highlights...
Article
Social media, such as blogs, are often seen as democratic entities that allow more voices to be heard than the conventional mainstream media as well as a balancing force against the arguably slanted elite media. A systematic comparison between social and mainstream media is necessary but challenging due to the scale and dynamic nature of modern com...
Article
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How do public administrators find information about the problems they confront at work? In particular, how and when do they reach across organizational boundaries to find answers? There are substantial potential obstacles to such searches for answers, especially in a system of decentralized governance such as the U.S. government. In this article, w...
Working Paper
Social capital is currently one of social structure‘s most prominent and debated manifestations. However, we have a limited understanding of how social ties as the basis of social capital form in the first place. From one perspective social capital is viewed as: "investment in social relations with expected returns in the marketplace" (Lin 2001, p....
Article
Full-text available
Social media, such as blogs, are often seen as democratic entities that allow more voices to be heard than the conventional mass or elite media. Some also feel that social media exhibits a balancing force against the arguably slanted elite media. A systematic comparison between social and mainstream media is necessary but challenging due to the sca...
Article
We examine the speed and extent to which members of the U.S. House of Representatives adopt emerging Web-based communication technologies. Given the growing centrality of communication for governance and the Web's growing role in effective public outreach, a rational actor approach would suggest that members of Congress should aggressively exploit...
Article
Deliberative theorists emphasize that citizens' capacity to become informed when given a motive and the opportunity to participate in politics is important for democratic citizenship. We assess this capacity among citizens using a deliberative field experiment. In the summer of 2006, we conducted a field experiment in which we recruited twelve curr...
Article
How do decentralized systems deal with innovation? In particular, how do they aggregate the myriad experiences of their component parts, facilitate diffusion of information, and encourage investments in innovation? This is a classic problem in the study of human institutions. It is also one of the biggest challenges that exists in the governance of...
Article
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If ignored, noncompliance with a treatment or nonresponse on outcome measures can bias estimates of treatment effects in a randomized experiment. To identify and estimate causal treatment effects in the case where compliance and response depend on unobservables, we propose the parametric generalized endogenous treatment (GET) model. GET incorporate...
Working Paper
Networks are often see as emergent and self-managed; and yet much of the research on networks examines how networks affect the effectiveness of systems and individuals. Is it possible to intervene in the configuration of a network to improve how it functions? Here we evaluate the impact of an intervention to change the array of relationships connec...
Article
What are the relational dimensions of politics? Does the way that people and organizations are connected to each other matter? Are our opinions affected by the people with whom we talk? Are legislators affected by lobbyists? Is the capacity of social movements to mobilize affected by the structure of societal networks? Powerful evidence in the lite...
Article
What are the ripple effects from structured deliberation sessions? To better understand the potential aggregate consequences of these (somewhat limited) opportunities, we focus on the social networks of participants, looking for the informational consequences of second-hand exposure. We report on the results of a field experiment in which randomly...
Article
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How do attitudes and social affiliations co-evolve? A long stream of research has focused on the relationship between attitudes and social affiliations. However, in most of this research the causal relationship between views and affiliations is difficult to discern definitively: Do people influence each other's views so that they converge over time...