Act-Sampling Bias and the Shrouding of Repeat Offending (2017)

Co-authored with Ian Ayres and Jessica Ladd.  In this paper, we explain how drawing naive conclusions from “act sampling”—sampling people’s actions instead of sampling the population—can make us grossly underestimate the proportion of repeat actors. We call this “act-sampling bias.” This bias is especially severe when the sample of known acts is small, as in sexual assault, which is among the least likely of crimes to be reported.  Virginia Law Review Online 94.

Confronting Hate Collectively (2017)

Co-authored with Elizabeth Levy Paluck.  To stop hate crimes, we must understand why perpetrators do what they do: the personal and social sources of their motivation. Research shows that potential perpetrators of hate crimes and bullying are actually quite conscious of the degree to which their community supports or condemns their actions.  PS: Political Science and Politics 50: 990–992.

The May 1 Marchers in Los Angeles: Overcoming Conflicting Frames, Bilingual Women Connectors, English-Language Radio, and Newly Politicized Spanish Speakers (2015)

Co-authored with Kim Yi Dionne, Darin DeWitt, and Michael Stone.  We study protest participants in the May 2006 immigration rights marches in Los Angeles. Analysis of original survey data of 876 march participants yields five main results.  First, despite substantial dispute among organizers on how to frame the marches, we find protest participants were similar across march locations organized by different coalitions.  Second, we find Spanish-English bilingual participants seemed to benefit from being in two media environments, as they reported more information sources about the protest events than monolingual participants.  Third, women reported hearing about the protest events from more information sources, and Spanish-English bilingual women reported hearing from more information sources than any other group, suggesting they acted as social connectors behind the massive participation.  Fourth, we confirm the importance of Spanish-language radio as an information source, but our data also point to the significance of television and English-language radio.  Finally, analyzing data of first-time protesters, we estimate the immigrant rights marches newly politicized 125,000 people in Los Angeles who spoke Spanish and not English.  Urban Affairs Review 51 (2015): 533–562.

Anonymous Procedures for Condorcet’s Model: Robustness, Nonmonotonicity, and Optimality (2010)

In Condorcet’s model of information aggregation, a group of people decides among two alternatives a and b, with each person getting an independent bit of evidence about which alternative is objectively superior.  I consider anonymous procedures, in which the group’s decision depends only on the number of people who report a or b, not their identities.  A procedure is called incentive compatible for a person if she wants to report truthfully given that others report truthfully.   I show that if an anonymous procedure is incentive compatible for both a person who is significantly biased toward a and a person who is significantly biased toward b, then it is incentive compatible for any person, regardless of his preferences and prior beliefs; also, if it is not trivial, it must be nonmonotonic, with an additional report for a sometimes decreasing the probability the group chooses a.  I define the “supermajority penalty” (SP) procedure and show that  when there are significant biases in both directions, the SP procedure is the optimal anonymous incentive compatible procedure from the point of view of an unbiased person.  Quarterly Journal of Political Science (2010) 5: 45–70.

Rational Choice and the Humanities: Excerpts and Folktales (2009)

I compare Beatrice and Benedick in William Shakespeare’s Much Ado About Nothing with Richard and Harrison in Richard Wright’s Black Boy.  I use this comparison to introduce the reader to game theory and to address some common criticisms, for example that rational choice theory assumes selfish and market-oriented individuals.  I then look at some trickster folktales from the African-American tradition, such as the well-known Brer Rabbit and the Tar Baby tale, and argue that these folktales can be understood as early primers in game-theoretic reasoning, long before game theory took mathematical shape in the 1950s.  I discuss some common misperceptions which come up in controversies over rational choice theory and how game theory and the humanities might interestingly interact.  Occasion: Interdisciplinary Studies in the Humanities (2009).

Rationally Constructing the Dimensions of the Political Sphere (2007)

This paper uses a game-theoretic model to show that the issue of social construction can in some form arise even in the stark conceptual world of completely rational and asocialized actors.  The paper suggests that it is possible that there are “hidden” issues, dimensions of political activity which can be politicized but are not because no individual wants to politicize them.  People have diverse preferences on these issues, but they play no role in political expression or decision making, and in fact are not visible to the outside observer.  Individuals here do not “keep quiet” out of social conditioning, conformity, or an inability to conceive of a different political reality, but because they are well aware that politicizing new issues has potentially risky real effects.  People who do try to expand the domain of political activity are people whom the currently understood dimensions of political activity place in a minority.  To create a new majority on a new dimension, it is not a matter of changing people’s preferences but of creating “class consciousness,” so that people know that others feel the same way they do.  The preferences which people use when voting, and their identity as majority or minority, are determined by constraints in people’s knowledge of each other.  These constraints are not exogenous but actively and rationally constructed by people through communication.  International Journal of Game Theory (2007) 35: 205–221.

Communication and Coordination in Social Networks (2000)

Here people playing a general coordination game use a communication network to let each other know their willingness to participate.  We obtain an exact characterization of which networks make coordination possible: we define a “minimal dependence network” of a coordination game, and show that coordination is possible if and only if the communication network contains a minimal dependence network.  Coordination games can be understood as placing people into a hierarchy of social roles or “stages”:  “initial adopters,” then “followers,” and so on down to “late adopters.”  We show that a communication network helps coordination in exactly two ways: by informing each stage about earlier stages, and by creating common knowledge within each stage.  We then consider two examples: first we show that  “low dimensional” networks can be better for coordination even though they have far fewer links than “high dimensional” networks; second we show that wide dispersion of “insurgents,” people predisposed toward participation, can be good for coordination but too much dispersion can be bad.  (Figure 3 in this paper has an error, as explained by Kris de Jaegher, to whom I am indebted.)  Review of Economic Studies (2000) 67: 1–16.

Structure and Strategy in Collective Action (1999)

This paper considers both structural and strategic influences on collective action.  Each person in a group wants to participate only if the total number participating is at least her threshold; people use a social network to communicate their thresholds.  People are strategically rational in that they are completely rational and also take into account that others are completely rational.  In several examples, I show that strategic rationality itself has structural implications otherwise not discernible.  Results include: cliques form the common knowledge crucial for collective action; dispersion of “insurgents,” people strongly predisposed toward collective action, can be good for collective action but too much dispersion can be bad; classic “bandwagon” models overstate the fragility of collective action.  American Journal of Sociology 105 (1999): 128–156.

Minority Voting Rights Can Maximize Majority Welfare (1999)

Recently, Lani Guinier argues against majority rule on fairness grounds, both abstractly and in the specific context of the representation of people of color in the United States. Since a majority can always get its way, a minority has little power and might not even participate in elections. Guinier suggests instead procedures which might distribute power more evenly, including “taking turns,” in which the majority gets to decide more often, but the minority gets to decide at least some of the time. Two centuries earlier, however, Condorcet argued for majority rule on the basis of efficient information aggregation: if each individual has an equal chance of having the correct opinion, then majority rule is most likely to select the better of two alternatives.

This paper takes Condorcet’s information aggregation model and adds voter heterogeneity: each voter has an idiosyncratic prior belief or preference which is the objectively better alternative. The main result is that given some prior beliefs, the best possible decision procedure for the majority involves taking turns, in the sense that with some probability the minority gets to decide even when outvoted by the majority. In other words, even the welfare criterion most favorable for the majority sometimes requires “special” minority voting power.  American Political Science Review (1999) 93: 85–97.

The Reeded Edge and the Phillips Curve: Money Neutrality, Common Knowledge, and Subjective Beliefs (1999)

This paper presents a simple two person auction model in which a seller and buyer make bids in units of money; however, the value of a unit of money, the rate at which money is redeemed into utility, is uncertain. The model is flexible enough so that beliefs and the kind of incomplete information can be specified freely, as if they were policy variables rather than structural features of the economy.

I show that money is neutral if and only if its value is common knowledge in the game theoretic sense: everyone knows what the value of a unit of money is, everyone knows that everyone knows, and so on. In other words, the informational requirements for neutrality are very strong: a monetary revaluation can have real effects even if everyone knows about it, for example.  I show that if the seller and buyer have different prior beliefs, then monetary policy can improve total gains from trade, measured objectively.  I also find an “optimal” level of inflation which captures the intuition that low levels of inflation encourage trade but high levels render money useless in trade.  Journal of Economic Theory 87 (1999): 49–71.

Culture, Circles, and Commercials: Publicity, Common Knowledge, and Social Coordination (1998)

This paper applies a game theoretic argument, that common knowledge is necessary for “solving” coordination problems, to a variety of cultural practices.  This argument helps in understanding how cultural practices such as mass ceremonies constitute power, how talking in inward-facing circles helps coordination, and why “social” goods tend to be advertised on popular and expensive television shows.  The main conclusion is that cultural practices, usually understood in terms of “meaning” or “content,” must also be understood in terms of “publicity,” or more precisely common knowledge generation.  Rationality and Society (1998) 10: 47–75.

Farsighted Coalitional Stability (1994)

I define the largest consistent set, a solution concept which applies to situations in which coalitions freely form but cannot make binding contracts, act publicly, and are fully “farsighted” in that a coalition considers the possibility that, once it acts, another coalition might react, a third coalition might in turn react, and so on, without limit.  I establish weak nonemptiness conditions and apply it to strategic and coalitional form games and majority rule voting.  I argue that it improves on the von Neumann-Morgenstern stable set as it is usually defined but is consistent with a generalization of the stable set as in the theory of social situations.  Journal of Economic Theory (1994) 63: 299–325.

Why Were Workers Whipped? Pain in a Principal-Agent Model (1990)

Violence, which seems inherently irrational, and economics, which calls itself the study of rational behavior, seem altogether unrelated.  But violence is often used in incentives—one reason a person threatens to hurt another is to get that person to do something.  This paper uses a model to show that threatening pain can be rational and that pain is inflicted on people who are poor in the sense of having bad alternatives.  The model corrects a confusion in previous models of slavery and helps explain why child and not adult labourers were beaten during the British industrial revolution.  Economic Journal (1990) 100: 1109–1121.

The Discrete Bid First Price Auction (1989)

In a first price auction in which buyers can bid only multiples of an increment and have uniformly distributed values, the expected price is less than the continuous bid price.  Economics Letters (1989) 31: 303–306.