Knowledge that Transforms

We explain how the common practice of size-discovery trade detracts from overall financial market efficiency. At each of a series of size-discovery sessions, traders report their desired trades, generating allocations of the asset and cash that rely on the most recent exchange price. Traders can thus mitigate exchange price impacts by waiting for size-discovery sessions. This waiting causes socially costly delays in the rebalancing of asset positions across traders. As the frequency of size-discovery sessions is increased, exchange market depth is further lowered by the traders’ reduced incentive to bid aggressively on the exchange, further delaying the rebalancing of positions, and more than offsetting the gains from trade that occur at each of the size-discovery sessions.

This article shows that the intensity of violence in Rwanda’s recent past can be traced back to the initial establishment of its pre-colonial state. Villages that were brought under centralized rule one century earlier experienced a doubling of violence during the state-organized 1994 genocide. Instrumental variable estimates exploiting differences in the proximity to Nyanza—an early capital—suggest that these effects are causal. Before the genocide, when the state faced rebel attacks, with longer state presence, violence is lower. Using data from several sources, including a lab-in-the-field experiment across an abandoned historical boundary, I show that the effect of the historical state is primarily sustained by culturally transmitted norms of obedience. The persistent effect of the pre-colonial state interacts with government policy: where the state developed earlier, there is more violence when the Rwandan government mobilized for mass killing and less violence when the government pursued peace.

We identify a new mechanism through which cultural diversity affects economic outcomes, based on a model of culture as shared cognition. Under this view, cultural diversity matters because it increases strategic uncertainty. The model can help better understand a variety of disparate evidence, including why homogeneous societies can be more conformist, why diverse societies may get stuck in a low-trust trap, why companies with a strong culture may fail to adopt superior work practices, and why autocratic rulers in diverse societies may overinvest in state capacity.

Traditional banking is built on four pillars: small and medium enterprise lending, insured deposit taking, access to lender of last resort (LOLR), and prudential supervision. This article unveils the logic of the quadrilogy by showing that it emerges naturally as an equilibrium outcome in a game between banks and the government. A key insight is that regulation and public insurance services (LOLR, deposit insurance) are complementary. The model also shows how prudential regulation must adjust to the emergence of shadow banking and rationalizes structural remedies to counter bogus liquidity hoarding and financial contagion: ring-fencing between regulated and shadow banking and the sharing of liquidity in centralized platforms.

We use survey questions about spending in hypothetical scenarios to investigate features of propensities to consume that are useful for distinguishing between consumption theories. We find that (1) responses to unanticipated gains are vastly heterogeneous (either zero or substantially positive); (2) responses increase in the size of the gain, driven by the extensive margin of spending adjustments; (3) responses to losses are much larger and more widespread than responses to gains; and (4) even those with large responses to gains do not respond to news about future gains. These four findings suggest that limited access to disposable resources, and frictions in adjusting consumption, are important determinants of consumption behaviour. We also find that (5) households do not respond to the offer of a one-year interest-free loan, suggesting that this is not a consequence of short-term credit constraints; and (6) people do cut spending in response to news about future losses, suggesting that neither is this a consequence of myopia. A calibrated precautionary savings model with utility costs of changing consumption, and a sufficient fraction of low-wealth households, can account for these features of propensities to consume on both the extensive and intensive margins.

In this paper, we use two comprehensive micro-data sets to study how the distribution of mortgage debt evolved during the 2000s housing boom. We show that the allocation of mortgage debt across the income distribution remained stable, as did the allocation of real estate assets. Any theory of the boom must replicate these facts, and a general equilibrium model shows that doing so requires two elements: (1) an exogenous shock that increases expected house price growth or, alternatively, reduces interest rates and (2) financial markets that endogenously relax borrowing constraints in response to the shock. Empirically, the endogenous relaxation of constraints was largely accomplished with subprime lending, which allowed the mortgage debt of low-income households to increase at the same rate as that of high-income households.

We model the building of a city, estimate parameters of the model, and calculate welfare losses from institutional frictions encountered in changing land-use. We distinguish formal and slum construction technologies; in contrast to slums, formal structures can be built tall, are durable, and non-malleable. As the city grows areas are initially developed informally, then formally, and then redeveloped periodically. Slums are modelled as a technology choice; however, institutional frictions in land markets may hinder their conversion to formal usage that requires secure property rights. Using unique data on Nairobi for 2003 and 2015, we develop a novel set of facts that support assumptions of the model, estimate all parameters of the model, and calculate welfare losses of conversion frictions. We track the dynamic evolution of the city and compare it with model predictions. In the core city formal sector, about a third of buildings were torn down over 12 years and replaced by buildings on average three times higher. For slums in older areas near the centre, even after buying out slumlords, overcoming institutional frictions would yield gains amounting to about $18,000 per slum household, thirty times typical annual slum rent payments.

The structural-change literature typically assumes that investment is produced in manufacturing. We establish that this assumption is counterfactual: in the postwar U.S., the share of services value added in investment expenditure has been steadily growing. We develop a new model that features structural change in investment and consumption, characterize its equilibrium properties, and provide empirical support for it. We establish that modelling structural change in investment leads to three novel insights: constant TFP growth in all sectors is inconsistent with the existence of aggregate balanced growth with structural change; the sector with the slowest TFP growth absorbs all resources asymptotically; technical change is endogenously investment-biased.

Observed choices between risky lotteries are difficult to reconcile with expected utility maximization, both because subjects appear to be too risk averse with regard to small gambles for this to be explained by diminishing marginal utility of wealth, as stressed by Rabin (2000), and because subjects’ responses involve a random element. We propose a unified explanation for both anomalies, similar to the explanation given for related phenomena in the case of perceptual judgments: they result from judgments based on imprecise (and noisy) mental representations of the decision situation. In this model, risk aversion results from a sort of perceptual bias—but one that represents an optimal decision rule, given the limitations of the mental representation of the situation. We propose a quantitative model of the noisy mental representation of simple lotteries, based on other evidence regarding numerical cognition, and test its ability to explain the choice frequencies that we observe in a laboratory experiment.

This article characterizes optimal compensation contracts in principal-agent settings in which the consequences of the agent’s action are only observed over time. The optimal timing of pay trades off the costs of deferred compensation arising from the agent’s relative impatience and potential consumption smoothing needs against the benefit of exploiting additional informative signals. By capturing this information benefit of deferral in terms of the likelihood ratio dynamics, our characterization covers general signal processes in a unified setting. With bilateral risk neutrality and agent limited liability, optimal contracts are high-powered and stipulate at most two payout dates. If the agent is additionally risk-averse, payouts are contingent on performance exceeding a hurdle that is increasing over time. We obtain clear-cut predictions on how the duration of optimal compensation depends on the nature of information arrival as well as agent characteristics and derive implications for the maturity structure of securities in financial contracting settings.