Knowledge that Transforms

We experimentally varied information mailed to 87,000 households in California’s health insurance marketplace to study the role of frictions in insurance take-up. Reminders about the enrollment deadline raised enrollment by 1.3 pp (16 percent) in this typically low take-up population. Heterogeneous effects of personalized subsidy information indicate misperceptions about program benefits. Consistent with an adverse selection model with frictional enrollment costs, the intervention lowered average spending risk by 5.1 percent, implying that marginal respondents were 37 percent less costly than inframarginal consumers. We observe the largest positive selection among low income consumers, who exhibit the largest frictions in enrollment. Finally, we estimate the implied value of the letter intervention to be $25 to $53 per month in subsidy dollars. These results suggest that frictions may partially explain low take-up for marketplace insurance, and that interventions reducing them can improve enrollment and market risk in exchanges. (JEL C93, G22, G52, H75, I13)

We study a major new entry in the French mobile telecommunications market, followed by the introduction of fighting brands by the three incumbents. Using an empirical oligopoly model, we find that the incumbents’ fighting brand strategies are difficult to rationalize as unilateral best responses. Instead, their strategies are consistent with a breakdown of tacit semi-collusion: before entry, the incumbents could successfully coordinate on restricting product variety to avoid cannibalization; after entry, this outcome became harder to sustain because of increased business stealing incentives. Consumers gained considerably from the added variety and, to a lesser extent, from the incumbents’ price responses. (JEL L13, L21, L96, M31)

Digitization has led to many new creative products, straining the capacity of professional critics and consumers. Yet, the digitization of retailing has also delivered new crowd-based sources of pre-purchase information. We compare the relative impacts of professional critics and crowd-based Amazon star ratings on consumer welfare in book publishing. Using various fixed effects and discontinuity-based empirical strategies, we estimate their causal impacts on sales. We use these causal estimates to calibrate a structural demand model. The aggregate effect of star ratings on consumer surplus is, in our baseline estimates, more than ten times the effect of traditional review outlets. (JEL D83, L15, L81, L82)

Vote-buying mechanisms allow agents to express any level of support for their preferred alternative at an increasing cost. Focusing on large societies with wealth inequality, we prove that the class of binary social choice rules implemented by well-behaved vote-buying mechanisms is indexed by a single parameter, which determines the importance assigned to the agents' willingness to pay to affect outcomes and to the number of supporters for each alternative. This parameter depends solely on the elasticity of the cost function near its origin: as this elasticity decreases, the intensities of support matter relatively more for outcomes than the supporters' count.

We explore how taste projection—the tendency to overestimate how similar others’ tastes are to one’s own—affects bidding in auctions. In first-price auctions with private values, taste projection leads bidders to exaggerate the intensity of competition and, consequently, to overbid—irrespective of whether values are independent, affiliated, or (a)symmetric. Moreover, the optimal reserve price is lower than the rational benchmark, and decreasing in the extent of projection and the number of bidders. With an uncertain common-value component, projecting bidders draw distorted inferences about others’ information. This misinference is stronger in second-price and English auctions, reducing their allocative efficiency compared to first-price auctions. (JEL D11, D44, D82, D83)

We introduce a set-valued solution concept, M equilibrium, to capture empirical regularities from over half a century of game-theory experiments. We show M equilibrium serves as a meta theory for various models that hitherto were considered unrelated. M equilibrium is empirically robust and, despite being set-valued, falsifiable. We report results from a series of experiments comparing M equilibrium to leading behavioral-game-theory models and demonstrate its virtues in predicting observed choices and stated beliefs. Data from experimental games with a unique pure-strategy Nash equilibrium and multiple M equilibria exhibit coordination problems that could not be anticipated through the lens of existing models.

Several K-12 and university systems have adopted race-neutral affirmative action in place of race-based alternatives. This paper explores whether these plans are effective substitutes for racial quotas in Chicago Public Schools (CPS), which now employs a race-neutral, place-based affirmative action system at its selective exam high schools. The CPS plan is ineffective compared to plans that explicitly consider race: about three-quarters of the reduction in average entrance scores at the top schools could have been avoided with the same level of racial diversity. Moreover, the CPS plan is less effective at adding low-income students than was the previous system of racial quotas. We develop a theoretical framework that motivates quantifying the inefficiency of race-neutral policies based on the distortion in student preparedness they create for a given level of diversity and use it to evaluate several alternatives. The CPS plan can be improved in several ways, but no race-neutral policy restores minority representation to prior levels without substantially greater distortions, implying significant efficiency costs from prohibitions on the explicit use of race. (JEL H75, I21, I28, J15)

Most individual life insurance policies lapse, with lapsers cross-subsidizing non-lapsers. We show that policies and lapse patterns predicted by standard rational expectations models are the opposite of those observed empirically. We propose two behavioral models consistent with the evidence: (i) consumers forget to pay premiums and (ii) consumers understate future liquidity needs. We conduct two surveys with a large insurer. New buyers believe that their own lapse probabilities are small compared to the insurer’s actual experience. For recent lapsers, forgetfulness accounts for 37.8 percent of lapses while unexpected liquidity accounts for 15.4 percent. (JEL D91, G22, G52)

Mistakes and overconfidence in detecting lies could help lies spread. Participants in our experiments observe videos in which senders either tell the truth or lie, and are incentivized to distinguish between them. We find that participants fail to detect lies, but are overconfident about their ability to do so. We use these findings to study the determinants of sharing and its effect on lie detection, finding that even when incentivized to share truthful videos, participants are more likely to share lies. Moreover, the receivers are more likely to believe shared videos. Combined, the tendency to believe lies increases with sharing. (JEL C91, D83, D91, L82)

This paper studies the large concentration of retirement behavior around statutory retirement ages, a puzzling stylized fact. To investigate this fact, I estimate bunching responses to 644 pension benefit discontinuities, using administrative data on the universe of German retirees. Financial incentives alone cannot explain retirement patterns, but there is a large direct effect of statutory retirement ages. I argue that the framing of statutory ages as reference points for retirement provides a plausible explanation. Simulations based on a model with reference dependence highlight that shifting statutory ages via pension reforms is an effective policy to influence retirement behavior. (JEL D91, H55, J26, J32)