@unpublished {78,
	title = {Naive Learning with Uninformed Agents},
	year = {2021},
	type = {Working Paper},
	abstract = {The DeGroot model has emerged as a credible alternative to the standard Bayesian model for studying learning on networks, offering a natural way to model naive learning in a complex setting. One unattractive aspect of this model is the assumption that the process starts with every node in the network having a signal. We study a natural extension of the DeGroot model that can deal with sparse initial signals. We show that an agent{\textquoteright}s social influence in this generalized DeGroot model is essentially proportional to the number of uninformed nodes who will hear about an event for the first time via this agent. This characterization result then allows us to relate network geometry to information aggregation. We show information aggregation preserves {\textquotedblleft}wisdom{\textquotedblright} in the sense that initial signals are weighed approximately equally in a model of network formation that captures the sparsity, clustering, and small-worlds properties of real-world networks. We also identify an example of a network structure where essentially only the signal of a single agent is aggregated, which helps us pinpoint a condition on the network structure necessary for almost full aggregation. Simulating the modeled learning process on a set of real world networks, we find that there is on average 21.6\% information loss in these networks. We also explore how correlation in the location of seeds can exacerbate aggregation failure. Simulations with real world network data show that with clustered seeding, information loss climbs to 35\%.},
	author = {Abhijit Banerjee and Arun Chandrasekhar and Emily Breza and Markus Mobius}
}
@unpublished {80,
	title = {When Celebrities Speak: A Nationwide Twitter Experiment Promoting Vaccination in Indonesia},
	year = {2018},
	type = {Working Paper},
	abstract = {Celebrity endorsements are often sought to influence public opinion. We ask whether celebrity endorsement per se has an effect beyond the fact that their statements are seen by many, and whether on net their statements actually lead people to change their beliefs. To do so, we conducted a nationwide Twitter experiment in Indonesia with 46 high-profile celebrities and organizations, with a total of 7.8 million followers, who agreed to let us randomly tweet or retweet content promoting immunization from their accounts. Our design exploits the structure of what information is passed on along a retweet chain on Twitter to parse reach versus endorsement effects. Endorsements matter: tweets that users can identify as being originated by a celebrity are far more likely to be liked or retweeted by users than similar tweets seen by the same users but without the celebrities{\textquoteright} imprimatur. By contrast, explicitly citing sources in the tweets actually reduces diffusion. By randomizing which celebrities tweeted when, we find suggestive evidence that overall exposure to the campaign may influence beliefs about vaccination and knowledge of immunization-seeking behavior by one{\textquoteright}s network. Taken together, the findings suggest an important role for celebrity endorsement.},
	author = {Vivi Alatas and Arun G. Chandrasekhar and Markus M. Mobius and Ben Olken and Cindy Paladines}
}
@unpublished {55,
	title = {The Impact of Aggregators on Internet News Consumption},
	year = {2017},
	abstract = {A policy debate centers around the question whether news aggregators such as Google News decrease or increase traffic to online news sites. One side of the debate, typically espoused by publishers, views aggregators as substitutes for traditional news consumption because aggregators{\textquoteright} landing pages provide snippets of news stories and therefore reduce the incentive to click on the linked articles. Defendants of aggregators, on the other hand, view aggregators as complements because they make it easier to discover news and therefore drive traffic to publishers. This debate has received particular attention in the European Union where two countries, Germany and Spain, enacted copyright reforms that allow newspapers to charge aggregators for linking to news snippets. In this paper, we use Spain as a natural experiment because Google News shut down all together in response to the reform in December 2014. We compare the news consumption of a large number of Google News users with a synthetic control group of similar non-Google News users. We find that the shutdown of Google News reduces overall news consumption by about 20\% for treatment users, and it reduces page views on publishers other than Google News by 10\%. This decrease is concentrated around small publishers while large publishers do not see significant changes in their overall traffic. We further find that when Google News shuts down, its users are able to replace some but not all of the types of news they previously read. Post-shutdown, they read less breaking news, hard news, and news that is not well covered on their favorite news publishers. These news categories explain most of the overall reduction in news consumption, and shed light on the mechanisms through which aggregators interact with traditional publishers.},
	author = {Susan Athey and Markus Mobius and Jeno Pal}
}
@unpublished {63,
	title = {Social Networks and Vaccination Decisions},
	journal = {FRB of Boston Working Paper No. 07-12},
	year = {2017},
	month = {November 2007},
	abstract = {We combine survey responses, network data, and medical records in order to examine how friends affect the decision to get vaccinated against influenza. The random assignment of undergraduates to residential halls at a large private university generates exogenous variation in exposure to the vaccine, enabling us to credibly identify social effects. We find evidence of positive peer influences on health beliefs and vaccination choices. In addition, we develop a novel procedure to distinguish between different forms of social effects. Most of the impact of friends on immunization behavior is attributable to social learning about the medical benefits of the vaccine.},
	url = {http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1073143},
	author = {Neel Rao and Markus Mobius and Tanya Rosenblat}
}
@inbook {69,
	title = {Informal Transfers in Social Networks},
	booktitle = {The Oxford Handbook of the Economics of Networks},
	year = {2016},
	pages = {611-629},
	publisher = {Oxford University Press},
	organization = {Oxford University Press},
	abstract = {Social networks can facilitate informal lending and risk-sharing in situations where for-mal institutions such as banks and insurance companies do not exist. The social collateral approach provides an analytically tractable framework that can be used to analyze a wide range of informal transfers. Moreover, the approach is easily amenable to empirical analysis.},
	url = {https://doi.org/10.1093/oxfordhb/9780199948277.013.28},
	author = {Markus Mobius and Tanya Rosenblat}
}
@article {68,
	title = {Ethnic Discrimination: Evidence from China},
	journal = {European Economic Review},
	volume = {90},
	year = {2016},
	pages = {165-177},
	abstract = {We study the role of ethnicity in experimental labor markets where {\textquotedblleft}employers{\textquotedblright} determine wages of {\textquotedblleft}workers{\textquotedblright} who perform a real effort task. This task requires a true skill which we show is not affected by minority status. In some treatments, we provide subtle priming to employers about minority status of workers as commonly depicted on Chinese {\textquotedblleft}Hukou{\textquotedblright} identification system. We conduct our experiments at two sites located in provinces that differ by their historical shares of ethnic groups in the population. We find that: (1) Han and minority workers are equally productive in both provinces; (2) in the diverse province, there is no difference in the wages between Han and minority workers; (3) in the non-diverse province, minority workers receive 4\%-7\% lower wages than Han workers.},
	url = {https://doi.org/10.1016/j.euroecorev.2016.04.004},
	author = {Markus Mobius and Tanya Rosenblat}
}
@unpublished {62,
	title = {Measuring Trust in Peruvian Shantytowns},
	journal = {Working Paper},
	year = {2015},
	month = {September 2010},
	abstract = {This paper uses a microfinance field experiment in two Lima shantytowns to measure the relative importance of social networks and prices for borrowing. Our design randomizes the interest rate on loans provided by a microfinance agency, as a function of the social distance between the borrower and the cosigner. This design effectively varies the relative price (interest rate differential) of having a direct friend versus an indirect friend as a cosigner. After loans are processed, a second randomization relieves some cosigners from their responsibility. These experiments yield three main results. (1) As emphasized by sociologists, connections are highly valuable: having a friend cosigner is equivalent to 18 per cent of the face value of a 6 month loan. (2) While networks are important, agents do respond to price incentives and switch to a non-friend cosigner when the interest differential is large. (3) Relieving responsibility of the cosigner reduces repayment for direct friends but has no effect otherwise, suggesting that different social mechanisms operate between friends and strangers: Non-friends cosign known high types, while friends also accept low types because of social collateral or altruism.},
	author = {Dean Karlan and Markus Mobius and Tanya Rosenblat and Adam Szeidl}
}
@unpublished {56,
	title = {Treasure Hunt: Social Learning in the Field},
	year = {2015},
	abstract = {We seed noisy information to members of a real-world social network to study how information diffusion and information aggregation jointly shape social learning. Our environment features substantial social learning. We show that learning occurs via diffusion which is highly imperfect: signals travel only up to two steps in the conversation network and indirect signals are transmitted noisily. We then compare two theories of information aggregation: a naive model in which people double-count signals that reach them through multiple paths, and a sophisticated model in which people avoid double-counting by tagging the source of information. We show that to distinguish between these models of aggregation, it is critical to explicitly account for imperfect diffusion. When we do so, we find that our data are most consistent with the sophisticated tagged model.},
	author = {Markus Mobius and Tuan Phan and Adam Szeidl}
}
@unpublished {57,
	title = {The Evolution of Work},
	year = {2014},
	abstract = {The division of labor first increased during industrialization, and then decreased again after 1970 as job roles have expanded. In this paper, we explain these trends in the organization of work through a simple model, making two minimal assumptions: (a) machines require standardization to exploit economies of scale and (b) more customized products are subject to trends and fashions which make production tasks less predictable and a strict division of labor impractical. The model predicts capital-skill substitutability during industrialization and capital-skill complementarity in the maturing industrial economy: At the onset of industrialization, the market supports only a small number of generic varieties which can be mass-produced under a strict division of labor. Then, thanks to productivity growth, niche markets gradually expand, producers eventually move into customized production, and the division of labor decreases again. We test our model by exploiting the time-lags in the introduction of bar-coding in three-digit SIC manufacturing industries in the U.S.. We find that both increases in investments in computers and bar-coding have led to skill-upgrading. However, consistent with our model bar-coding has affected mainly the center of the skill distribution by shifting demand away from the high-school educated to the less-than-college educated.},
	author = {Markus Mobius and Raphael Schoenle}
}
@unpublished {58,
	title = {Managing Self-Confidence},
	journal = {working paper},
	year = {2014},
	abstract = {Stylized evidence suggests that people process information about their own ability in a biased manner. We provide a precise characterization of the nature and extent of these biases. We directly elicit experimental subjects{\textquoteright} beliefs about their relative performance on an IQ quiz and track the evolution of these beliefs in response to noisy feedback. Our main result is that subjects update as if they misinterpret the information content of signals, but then process these misinterpreted signals like Bayesians. Specifically, they are asymmetric, over-weighting positive feedback relative to negative, and conservative, updating too little in response to both positive and negative feedback. These biases are substantially less pronounced in a placebo experiment where ego is not at stake, suggesting they are motivated rather than cognitive. Consistent with Bayes{\textquoteright} rule, on the other hand, updating is invariant to priors (and over time) and priors are sufficient statistics for past information. Based on these findings, we build a model that theoretically derives the optimal bias of a decision-maker with ego utility and show that it naturally gives rise to both asymmetry and conservatism as complementary strategies in self-confidence management.},
	author = {Markus Mobius and Muriel Niederle and Paul Niehaus and Tanya Rosenblat}
}
@article {43,
	title = {Buy-it-now or Take-a-chance: Price Discrimination through Randomized Auctions},
	journal = {Management Science},
	volume = {60},
	number = {12},
	year = {2014},
	pages = {2927 - 2948},
	abstract = {Increasingly detailed consumer information makes sophisticated price discrimination possible. At fine levels of aggregation, demand may not obey standard regularity conditions. We propose a new randomized sales mechanism for such environments. Bidders can "buy-it-now" at a posted price, or "take-a-chance" in an auction where the top d \&gt; 1 bidders are equally likely to win. The randomized allocation incentivizes high valuation bidders to buy-it-now. We analyze equilibrium behavior, and apply our analysis to advertiser bidding data from Microsoft Advertising Exchange. In counterfactual simulations, our mechanism increases revenue by 4.4\% and consumer surplus by 14.5\% compared to an optimal second-price auction.},
	url = {https://doi.org/10.1287/mnsc.2014.2009},
	author = {L. Elisa  Celis and Gregory Lewis and Markus Mobius and Hamid Nazerzadeh}
}
@article {44,
	title = {Consumption Risk-sharing in Social Networks},
	journal = {American Economic Review},
	volume = {104},
	number = {1},
	year = {2014},
	pages = {149-82},
	abstract = {We develop a model in which connections between individuals serve as social collateral to enforce informal insurance payments. We show that: (1) The degree of insurance is governed by the expansiveness of the network, measured with the per capita number of connections that groups have with the rest of the community. Two-dimensional networks---like real-world networks in Peruvian villages---are sufficiently expansive to allow very good risk-sharing. (2) In second-best arrangements, insurance is local: agents fully share shocks within, but imperfectly between endogenously emerging risk-sharing groups. We also discuss how endogenous social collateral affects our results. (JEL D02, D31, D70)},
	url = {https://doi.org/10.1257/aer.104.1.149},
	author = {Attila Ambrus and Markus Mobius and Adam Szeidl}
}
@article {45,
	title = {Social Learning in Economics},
	journal = {Annual Review of Economics},
	volume = {6},
	number = {1},
	year = {2014},
	pages = {827-847},
	abstract = {Social learning is a rapidly growing field for empirical and theoretical research in economics. We encounter social learning in many economically important phenomena, such as the adoption of new products and technologies or job search in labor markets. We review the existing empirical and theoretical literatures and argue that they have evolved largely independently of each other. This suggests several directions for future research that can help bridge the gap between both literatures. For example, the theory literature has come up with several models of social learning, ranging from na{\"\i}ve DeGroot models to sophisticated Bayesian models whose assumptions and predictions need to be empirically tested. Alternatively, empiricists have often observed that social learning is more localized than existing theory models assume, and that information can decay along a transmission path. Incorporating these findings into our models might require theorists to look beyond asymptotic convergence in social learning.},
	url = {http://www.annualreviews.org/doi/abs/10.1146/annurev-economics-120213-012609},
	author = {Markus Mobius and Tanya Rosenblat}
}
@unpublished {59,
	title = {The Impact of News Aggregators on Internet News Consumption: The Case of Localization},
	year = {2012},
	abstract = {This paper analyzes the impact of news aggregators on the quantity and composition of internet news consumption. In principle, news aggregators can be a substitute or a complement to the news outlets who invest in the creation of news stories. A policy debate centers around the decrease in the incentives for news creation that results if readers choose to consume their news through aggregators without clicking through to the news websites or generating any revenue for the outlets. This paper provides a case analysis of an example where Google News added local content to their news home page for users who chose to enter their location. Using a dataset of user browsing behavior, we compare users who adopt the localization feature to a sample of control users who are similar to the treatment users in terms of recent internet news consumption. We find that users who adopt the localization feature subsequently increase their usage of Google News, which in turn leads to additional consumption of local news. Users also navigate directly to the new sites they have discovered, further increasing their local news consumption. The increase in local news consumption diminishes over time, however, and in the longer run most of the additional local news consumption derives from increased Google News usage. Patterns of news consumption change: users read a wider variety of outlets, more outlets that are new to them, and a larger fraction of their news {\textquotedblleft}home page{\textquotedblright} views come from Google News rather than the home page of other news outlets. Thus, the inclusion of local content by Google News had mixed effects on local outlets: it increased their traffic, especially in the short run, but it also increased the reliance of users on Google News for their choices of news, and increased the dispersion of user attention across outlets.},
	author = {Susan Athey and Markus Mobius}
}
@unpublished {61,
	title = {Death through Success: The Rise and Fall of Local Service Competition at the Turn of the Century},
	year = {2011},
	abstract = {This paper develops a model of delayed network effects to explore the curious dynamics of competition in the local telephone market between AT\&amp;T and the {\textquoteright}Independents{\textquoteright} at the turn of the century. In the early years of telephone diffusion, local service competition between these two non-interconnected networks became widespread, but declined rapidly when diffusion rates started to slow down after 1907. The analysis is based on the observation that urban markets subdivide into social {\textquoteright}islands{\textquoteright} along geographical and socio-economic dimensions: users are more likely to communicate with subscribers {\textquoteright}inside{\textquoteright} their island than with those {\textquoteright}outside{\textquoteright} it. A simple dynamic model demonstrates how minority networks can thrive and preserve their market share at a low state of development when islands form essentially independent niche markets. As the industry matures, these niches {\textquoteright}grow{\textquoteright} together and standardization occurs. The implications of the model are confirmed using a small panel data set of US cities.},
	author = {Markus Mobius}
}
@unpublished {60,
	title = {Social Networks and Consumer Demand},
	year = {2011},
	month = {January 2011},
	author = {Markus Mobius and Paul Niehaus and Tanya Rosenblat}
}
@proceedings {46,
	title = {Buy-it-now or Take-a-chance: A Simple Sequential Screening Mechanism},
	journal = {Proceedings of the 20th international conference on World wide web},
	volume = {WWW {\textquoteright}11},
	number = {March 2011},
	year = {2011},
	pages = {147-156},
	publisher = {International World Wide Web Conference Committee},
	address = {Hyderabad, India},
	abstract = {We present a simple auction mechanism which extends the second-price auction with reserve and is truthful in expectation. This mechanism is particularly effective in private value environments where the distribution of valuations are irregular. Bidders can {\textquotedblleft}buy-it-now{\textquotedblright}, or alternatively {\textquotedblleft}takea- chance{\textquotedblright} where the top d bidders are equally likely to win. The randomized take-a-chance allocation incentivizes high valuation bidders to buy-it-now. We show that for a large class of valuations, this mechanism achieves similar allocations and revenues as Myerson{\textquoteright}s optimal mechanism, and outperforms the second-price auction with reserve. In addition, we present an evaluation of bid data from Microsoft{\textquoteright}s AdECN platform. We find the valuations are irregular, and counterfactual experiments suggest our BINTAC mechanism would improve revenue by 11\% relative to an optimal second-price mechanism with reserve.},
	url = {https://dl.acm.org/citation.cfm?id=1963429},
	author = {L. Elisa  Celis and Gregory Lewis and Markus Mobius and Hamid Nazerzadeh}
}
@article {47,
	title = {What Do We Expect From Our Friends?},
	journal = {Journal of European Economic Association},
	volume = {8},
	number = {1},
	year = {2010},
	pages = {120-138},
	abstract = {We conduct a field experiment in a large real-world social network to examine how subjects expect to be treated by their friends and by strangers who make allocation decisions in modified dictator games. While recipients{\textquoteright} beliefs accurately account for the extent to which friends will choose more generous allocations than strangers (i.e. directed altruism), recipients are not able to anticipate individual differences in the baseline altruism of allocators (measured by giving to an unnamed recipient, which is predictive of generosity towards named recipients). Recipients who are direct friends with the allocator, or even recipients with many common friends, are no more accurate in recognizing intrinsically altruistic allocators. Recipient beliefs are significantly less accurate than the predictions of an econometrician who knows the allocator{\textquoteright}s demographic characteristics and social distance, suggesting recipients do not have information on unobservable characteristics of the allocator.},
	url = {https://doi.org/10.1162/qjec.2009.124.4.1815},
	author = {Stephen Leider and Markus Mobius and Tanya Rosenblat and Quoc-Anh Do}
}
@article {48,
	title = {Directed Altruism and Enforced Reciprocity in Social Network},
	journal = {Quarterly Journal of Economics},
	volume = {124},
	number = {1},
	year = {2009},
	pages = {1815{\textendash}1851},
	abstract = {We conduct online field experiments in large real-world social networks in order to decompose prosocial giving into three components: (1) baseline altruism toward randomly selected strangers, (2) directed altruism that favors friends over random strangers, and (3) giving motivated by the prospect of future interaction. Directed altruism increases giving to friends by 52 percent relative to random strangers, while future interaction effects increase giving by an additional 24 percent when giving is socially efficient. This finding suggests that future interaction affects giving through a repeated game mechanism where agents can be rewarded for granting efficiency-enhancing favors. We also find that subjects with higher baseline altruism have friends with higher baseline altruism.},
	url = {https://doi.org/10.1162/qjec.2009.124.4.1815},
	author = {Stephen Leider and Markus Mobius and Tanya Rosenblat and Quoc-Anh Do}
}
@article {49,
	title = {Trust and Social Collateral},
	journal = {Quarterly Journal of Economics},
	volume = {124},
	number = {3},
	year = {2009},
	pages = {1307{\textendash}1361},
	abstract = {This paper builds a theory of trust based on informal contract enforcement in social networks. In our model, network connections between individuals can be used as social collateral to secure informal borrowing. We dene network-based trust as the highest amount one agent can borrow from another agent, and derive a reduced-form expression for this quantity which we then use in three applications. (1) We predict that dense networks generate bonding social capital that allows transacting valuable assets, while loose networks create bridging social capital that improves access to cheap favors like information. (2) For job recommendation networks, we show that strong ties between employers and trusted recommenders reduce asymmetric information about the qualityof job candidates. (3) Using data from Peru, we show empirically that network-based trust predicts informal borrowing, and we structurally estimate and test our model.},
	url = {https://doi.org/10.1162/qjec.2009.124.3.1307},
	author = {Dean Karlan and Markus Mobius and Tanya Rosenblat and Adam Szeidl}
}
@article {50,
	title = {Community Size and Network Closure},
	journal = {American Economic Review Papers and Proceedings},
	volume = {97},
	number = {2},
	year = {2007},
	pages = {80-85},
	url = {http://www.jstor.org/stable/30034425},
	author = {Hunt Allcott and Dean Karlan and Markus Mobius and Tanya Rosenblat and Adam Szeidl}
}
@article {51,
	title = {Existence of Equilibrium in Large Double Auctions},
	journal = {Journal of Economic Theory},
	volume = {133},
	number = {1},
	year = {2007},
	pages = {550-567},
	abstract = {We show the existence of a pure strategy, symmetric, increasing equilibrium in double auction markets with correlated, conditionally independent private values and many participants. The equilibrium we find is arbitrarily close to fully revealing as the market size grows. Our results provide strategic foundations for price-taking behavior in large markets.},
	url = {https://doi.org/10.1016/j.jet.2005.07.014},
	author = {Drew Fudenberg and Markus Mobius and Adam Szeidl}
}
@article {52,
	title = {Why Beauty Matters},
	journal = {American Economic Review},
	volume = {96},
	number = {1},
	year = {2006},
	pages = {222-235},
	abstract = {We decompose the beauty premium in an experimental labor market where "employers" determine wages of "workers" who perform a maze-solving task. This task requires a true skill which we show to be una{\textregistered}ected by physical attractiveness. We find a sizable beauty premium and can identify three transmission channels. (1) Physically-attractive workers are more confident and higher confidence increases wages. (2) For a given level of confidence, physically-attractive workers are (wrongly) considered more able by employers. (3) Controlling for worker confidence, physically-attractive workers have oral skills (such as communication and social skills) that raise their wages when they interact with employers. Our methodology can be adapted to study the sources of discriminatory pay differentials in other settings.},
	url = {https://doi.org/10.1257/000282806776157515},
	author = {Tanya Rosenblat and Markus Mobius}
}
@article {53,
	title = {Competing Auctions},
	journal = {Journal of European Economic Association},
	volume = {2},
	number = {1},
	year = {2004},
	pages = {30-66},
	abstract = {This paper examines a simple model of competing auction sites to give some insights into the concentration of auction markets. In our model, there are B ex-ante identical buyers, each with unit demand, and S sellers, each with a single unit of the good to sell and a reservation value of zero. At the start of the model, buyers and sellers simultaneously choose between two possible locations. Buyers then learn their private values for the good, and a uniform-price auction is held at each location. This is a very stark model, but we believe that it provides some useful insights, and that it serves as a benchmark case for richer and more realistic models.},
	url = {https://doi.org/10.1162/154247604323015472},
	author = {Glenn Ellison and Drew Fudenberg and Markus Mobius}
}
@article {54,
	title = {Getting Closer or Drifting Apart},
	journal = {Quarterly Journal of Economics},
	volume = {119},
	number = {3},
	year = {2004},
	pages = {971-1009},
	abstract = {Advances in communication and transportation technologies have the potential to bring people closer together and create a {\textquoteleft}global village{\textquoteright}. However, they also allow heterogenous agents to segregate along special interests which gives rise to communities fragmented by type rather than geography. We show that lower communication costs should always decrease separation between individual agents even as group-based separation increases. Each measure of separation is pertinent for distinct types of social interaction. A group-based measure captures the diversity of group preferences that can have an impact on the provision of public goods. An individual measure correlates with the speed of information transmission through the social network that affects, for example, learning about job opportunities and new technologies. We test the model by looking at coauthoring between academic economists before and during the rise of the Internet in the 1990s.},
	url = {https://doi.org/10.1162/0033553041502199},
	author = {Tanya Rosenblat and Markus Mobius}
}
@unpublished {64,
	title = {Formation of Social Capital: An Experiment},
	year = {2002},
	month = {December 2002},
	abstract = {We study the formation of social capital in an environment where specialized agents have frequent diverse needs. This limits the potential of purely bilateral cooperation because the interaction frequency between any two particular agents is low. Such interactions usually invite defection by both sides unless agents are altruistic, or there exist information aggregation institutions that facilitate the use of group punishments. In a companion paper Gentzkow and Mobius (2002) develop a theory of how agents can cooperate even in a limited information environment as long as they can relay requests for help. This mechanism creates networks with long-term relationships which are continuously recombined to satisfy short-term needs. We test the theoretical predictions by conducting an experiment with two treatments: in the first treatment, agents can only utilize direct {\textquoteleft}favors{\textquoteright} while the second treatment adds the ability to provide indirect {\textquoteleft}favors{\textquoteright} as well. Our results help us understand how agents form and sustain weak links.},
	author = {Markus Mobius and Tanya Rosenblat}
}
@unpublished {66,
	title = {The Process of Ghetto Formation: Evidence from Chicago},
	year = {2001},
	month = {December 2001},
	author = {Markus Mobius and Tanya Rosenblat}
}
@unpublished {67,
	title = {Trading Favors},
	year = {2001},
	author = {Markus Mobius}
}
@unpublished {65,
	title = {On the Transition Between Monetary Regimes},
	year = {2001},
	month = {July 2001},
	abstract = {Historically, commodity money preceded fiat money. Standard search-theoretical models of money such as Kiyotaki and Wright (1989) cannot explain this transition because of multiple equilibria: a small infusion of fiat money with superior intrinsic characteristics into a commodity money equilibrium is always valued if agents believe in its acceptability. We propose a natural extension of the standard model in order to break this indeterminacy. We assume (1) that agents derive positive utility from consuming even non-favorite commodities and (2) that agents have to consume regularly. We find that agents accept only commodity money if search frictions are large. Fiat money can become valuable in sufficiently advanced economies with small search frictions.},
	author = {Tanya Rosenblat and Markus Mobius}
}
@unpublished {75,
	title = {The Formation of Ghettos as a Local Interaction Phenomenon},
	year = {2000},
	abstract = {I analyze a simple evolutionary model of residential segregation based on decentralized racism which extends Schelling{\textquoteright}s (1972) well-known tipping model by allowing for local interaction between residents. The richer set-up explains not only the persistence of ghettos, but also provides a mechanism for the rapid transition from an all-white to an all-black equilibrium. On one-dimensional streets segregation arises once a group becomes sufficiently dominant in the housing market. However, the resulting ghettos are not persistent, and periodic shifts in the market can give rise to "avenue waves". On two-dimensional inner-cities, on the other hand, ghettos can be persistent due to the \encircling phenomenon" if the majority ethnic group is sufficiently less tolerant than the minority. I review the history of residential segregation in the US and argue that my model can explain the rapid rise of almost exclusively black ghettos at the beginning of the 20th century. For the analysis of my model I introduce a new technique to characterize the medium and long-run stochastic dynamics. I show that clustering predicts the behavior of large-scale processes with many agents more accurately than standard stochastic stability analysis, because the latter concept overemphasizes the {\textquoteright}noisy{\textquoteright} part of the stochastic dynamics.},
	author = {Markus Mobius}
}
