Navin Kartik Publications

Many US colleges now use test-optional admissions. A frequent claim is that by not seeing standardized test scores, a college can admit a student body it prefers, say, with more diversity. But how can observing less information improve decisions? This paper proposes that test-optional policies are a response to social pressure on admission decisions. We model a college that bears disutility when it makes admission decisions that "society" dislikes. Going test optional allows the college to reduce its "disagreement cost." We analyze how missing scores are imputed and the consequences for the college, students, and society.

We study observational learning in environments with congestion costs: an agent's payoff from choosing an action decreases as more predecessors choose that action. Herds cannot occur if congestion on every action can get so large that an agent prefers a different action regardless of his beliefs about the state. To the extent that switching away from the more popular action reveals private information, it improves learning. The absence of herding does not guarantee complete (asymptotic) learning, however, as information cascades can occur through perpetual but uninformative switching between actions. We provide conditions on congestion costs that guarantee complete learning and conditions that guarantee bounded learning. Learning can be virtually complete even if each agent has only an infinitesimal effect on congestion costs. We apply our results to markets where congestion costs arise through responsive pricing and to queuing problems where agents dislike waiting for service.

We study the characteristics of self-selected candidates in corrupt political systems. Individuals differ along two dimensions of unobservable character: public spirit (altruism) and honesty (disutility from selling out to special interests). Both aspects combine to determine an individual's quality as governor. We characterize properties of equilibrium candidate pools for arbitrary costs of running for office, including when costs become vanishingly small. We explore how policy instruments such as the governor's compensation and anticorruption enforcement affect the expected quality of governance through candidate self-selection. We show that self-selection can have surprising implications for the effect of information disclosures concerning candidates' backgrounds.

We consider full implementation in complete-information environments when agents have an arbitrarily small preference for honesty. We offer a condition called separable punishment and show that when it holds and there are at least two agents, any social choice function can be implemented by a simple mechanism in two rounds of iterated deletion of strictly dominated strategies.

An agent advises a principal on selecting one of multiple projects or an outside option. The agent is privately informed about the projects' benefits and shares the principal's preferences except for not internalizing her value from the outside option. We show that for moderate outside option values, strategic communication is characterized by pandering: the agent biases his recommendation toward “conditionally better-looking” projects, even when both parties would be better off with some other project. A project that has lower expected value can be conditionally better-looking. We develop comparative statics and implications of pandering. Pandering is also induced by an optimal mechanism without transfers

We generalize the canonical problem of Nash implementation by allowing agents to voluntarily provide discriminatory signals, i.e., evidence. Evidence can either take the form of hard information or, more generally, have differential but nonprohibitive costs in different states. In such environments, social choice functions that are not Maskin-monotonic can be implemented. We formulate a more general property, evidence monotonicity, and show that this is a necessary condition for implementation. Evidence monotonicity is also sufficient for implementation in economic environments. In some settings, such as when agents have small preferences for honesty, any social choice function is evidence-monotonic. Additional characterizations are obtained for hard evidence. We discuss the relationship between the implementation problem where evidence provision is voluntary and a hypothetical problem where evidence can be chosen by the planner as part of an extended outcome space.

This note shows that the conventional outcome associated with Bertrand competition with homogenous products and different marginal costs is obtained in every Nash equilibrium in which firms use undominated strategies. This strengthens an existence result due to Blume (2003).

This paper studies a simple model of observational learning where agents care not only about the information of others but also about their actions. We show that despite complex strategic considerations that arise from forward-looking incentives, herd behavior can arise in equilibrium. The model encompasses applications such as sequential elections, public good contributions, and leadership charitable giving.

I study a model of strategic communication between an uninformed Receiver and an informed but upwardly biased Sender. The Sender bears a cost of lying, or more broadly, of misrepresenting his private information. The main results show that inflated language naturally arises in this environment, where the Sender (almost) always claims to be of a higher type than he would with complete information. Regardless of the intensity of lying cost, there is incomplete separation, with some pooling on the highest messages. The degree of language inflation and how much information is revealed depend upon the intensity of lying cost. The analysis delivers a framework to span a class of cheap-talk and verifiable disclosure games, unifying the polar predictions they make under large conflicts of interest. I use the model to discuss how the degree of manipulability of information can affect the trade-off between delegation and communication.

We study costs and benefits of differences of opinion between an adviser and a decision maker. Even when they share the same underlying preferences over decisions, a difference of opinion about payoff‐relevant information leads to strategic information acquisition and transmission. A decision maker faces a fundamental trade‐off: a greater difference of opinion increases an adviser's incentives to acquire information but exacerbates the strategic disclosure of any information that is acquired. Nevertheless, when choosing from a rich pool of opinion types, it is optimal for a decision maker to select an adviser with some difference of opinion. Centralization of authority is essential to harness these incentive gains since delegation to the adviser can discourage effort.

This paper reinterprets the evidence on lying or deception presented in Gneezy (Am. Econ. Rev. 95(1):384–394, 2005). We show that Gneezy’s data are consistent with the simple hypothesis that people are one of two kinds: either a person will never lie, or a person will lie whenever she prefers the outcome obtained by lying over the outcome obtained by telling the truth. This implies that so long as lying induces a preferred outcome over truth-telling, a person’s decision of whether to lie may be completely insensitive to other changes in the induced outcomes, such as exactly how much she monetarily gains relative to how much she hurts an anonymous partner. We run new but broadly similar experiments to those of Gneezy in order to test this hypothesis. While we also confirm that there is an aversion to lying in our subject population, our data cannot reject the simple hypothesis described above either.

This resurgence of interest in Condorcet’s approach was sparked by a key observation of David Austen-Smith and Jeffrey Banks (1996) that “naive” voting is generally not a Nash equilibrium of the voting game. That is, the optimal way to vote in a multiperson committee is not usually the same as the optimal way to vote in a committee of one, an issue overlooked by Condorcet and other nongame-theoretic analyses of his model. In fact, a voter’s strategic incentives generally depend on all the variables of the model: the size of the committee, the voting rule and procedure, the information structure, preferences, and so forth. Because such a simple model offers rich insights into the strategic considerations faced by voters, the CJM has played a prominent role in enhancing our understanding of voting mechanisms.

There are typically multiple equilibrium outcomes in the Crawford–Sobel (CS) model of strategic information transmission. This paper identifies a simple condition on equilibrium payoffs, called NITS (no incentive to separate), that selects among CS equilibria. Under a commonly used regularity condition, only the equilibrium with the maximal number of induced actions satisfies NITS. We discuss various justifications for NITS, including perturbed cheap‐talk games with nonstrategic players or costly lying. We also apply NITS to other models of cheap talk, illustrating its potential beyond the CS framework.

Austen-Smith and Banks [Cheap talk and burned money, J. Econ. Theory 91(1) (2000) 1–16] study how money burning can expand the set of pure cheap talk equilibria of Crawford and Sobel [Strategic information transmission, Econometrica 50(6) (1982) 1431–1451]. I identify an error in the main Theorem of Austen-Smith and Banks, and provide a variant that preserves some of the important implications. I also prove that cheap talk can be influential with money burning if and only if it can be influential without money burning. This strengthens a result of Austen-Smith and Banks, but uncovers other errors in their analysis. Finally, an open conjecture of theirs is proved correct.

We study a one-dimensional Hotelling-Downs model of electoral competition with the following innovation: a fraction of candidates have “character” and are exogenously committed to a campaign platform; this is unobservable to voters. Character is desirable, and a voter's utility is a convex combination of standard policy preferences and her assessment of a candidate's character. This structure induces a signaling game between strategic candidates and voters, since a policy platform affects voters' utilities not only directly, but also indirectly through inferences about a candidate's character. The model generates a number of predictions, starting with a failure of the median voter theorem.