Ingela Alger

Moral hazard, insurance, and some collusion

A risk-averse consumer purchases an insurance policy; if she suffers a loss, she may receive services from a provider to recover some of the loss. Only the consumer and the provider know if the loss has actually occurred. The providers behavior is uncertain. With some positive probability, the provider is honest, reporting the loss information truthfully to the insurer; with the complementary probability, the provider reports the information strategically, by writing a side-contract with the consumer to maximize the joint surplus of the provider-consumer coalition. We show that there is a loss of generality in considering only collusion-proof contracts, and characterize equilibria implemented by collusion-proof and noncollusion-proof contracts. When the probability of a provider acting collusively is small, the equilibrium contract is not collusion-proof but approximately first-best. When the probability of a provider acting collusively is large, the equilibrium contract is independent of this probability and identical to the equilibrium collusion-proof contract when the provider is collusive with probability 1.

A generalization of Hamilton's rule—Love others how much?

According to Hamiltons (1964a, b) rule, a costly action will be undertaken if its fitness cost to the actor falls short of the discounted benefit to the recipient, where the discount factor is Wrights index of relatedness between the two. We propose a generalization of this rule, and show that if evolution operates at the level of behavior rules, rather than directly at the level of actions, evolution will select behavior rules that induce a degree of cooperation that may differ from that predicted by Hamiltons rule as applied to actions. In social dilemmas there will be less (more) cooperation than under Hamiltons rule if the actions are strategic substitutes (complements). Our approach is based on natural selection, defined in terms of personal (direct) fitness, and applies to a wide range of pairwise interactions.

SCREENING ETHICS WHEN HONEST AGENTS CARE ABOUT FAIRNESS

A principal faces an agent with private information who is either honest or dishonest. Honesty involves revealing private information truthfully if the probability that the equilibrium allocation chosen by an agent who lies is small enough. Even the slightest intolerance for lying prevents full ethics screening whereby the agent is given proper incentives if dishonest and zero rent if honest. Still, some partial ethics screening may allow for taking advantage of the potential honesty of the agent, even if honesty is unlikely. If intolerance for lying is strong, the standard approach that assumes a fully opportunistic agent is robust.

A Theory of Fraud and Overtreatment in Experts Markets

Consumers often rely on an expert’s diagnosis to assess their needs. If the expert is also the seller of services, he may use his informational advantage to induce overtreatment, which is a pervasive phenomenon in experts markets. We offer and discuss conditions leading to equilibrium overtreatment in an otherwise purely competitive model. This market failure results from consumers’ ability to turn down an expert’s recommendation: experts defraud consumers to keep them uninformed, as this deters them from seeking a better price elsewhere.

Screening Ethics when Honest Agents Keep their Word

Using a principal-agent setting, we introduce honesty that requires pre-commitment. The principal offers a menu of mechanisms to screen ethics. Agents may misrepresent ethics. Dishonest agents may misrepresent the match with the assigned task (good or bad), while honest agents reveal the match honestly if they have pre-committed. Ethics-screening, that allows for match-screening with dishonest agents while leaving a lower rent to honest agents, is optimal if both honesty and a good match are likely. Otherwise the optimal mechanism is the standard second-best or the first-best (where dishonest agents misrepresent the match), if dishonesty is likely or unlikely respectively.

Does evolution lead to maximizing behavior

A long‐standing question in biology and economics is whether individual organisms evolve to behave as if they were striving to maximize some goal function. We here formalize this “as if” question in a patch‐structured population in which individuals obtain material payoffs from (perhaps very complex multimove) social interactions. These material payoffs determine personal fitness and, ultimately, invasion fitness. We ask whether individuals in uninvadable population states will appear to be maximizing conventional goal functions (with population‐structure coefficients exogenous to the individuals behavior), when what is really being maximized is invasion fitness at the genetic level. We reach two broad conclusions. First, no simple and general individual‐centered goal function emerges from the analysis. This stems from the fact that invasion fitness is a gene‐centered multigenerational measure of evolutionary success. Second, when selection is weak, all multigenerational effects of selection can be summarized in a neutral type‐distribution quantifying identity‐by‐descent between individuals within patches. Individuals then behave as if they were striving to maximize a weighted sum of material payoffs (own and others). At an uninvadable state it is as if individuals would freely choose their actions and play a Nash equilibrium of a game with a goal function that combines self‐interest (own material payoff), group interest (group material payoff if everyone does the same), and local rivalry (material payoff differences).

A Theory of Fraud and Over-Consumption in Experts Markets

Consumers often have to rely on an experts diagnosis to assess their needs. If the expert is also the seller of services, he may use his informational advantage to induce over-consumption. Empirical evidence suggests that over-consumption is a pervasive phenomenon in experts markets. We prove the existence of equilibrium over-consumption in an otherwise purely competitive model. This market failure results from the freedom of consumers to turn down an experts recommendation: experts defraud consumers in order to keep them uninformed, as this deters them from seeking a better price elsewhere. Our model also yields predictions on the diagnosis price that are in line with stylized facts, and provides a theory for why risk-neutral consumers would demand extended warranties on durables.

Consumer Strategies Limiting the Monopolist's Power: Multiple and Joint Purchases

I characterize the menu of bundles (price-quantity combinations) offered by a monopolist when consumers can buy several bundles, share bundles with others, or do both, in a two-type setting. I find that although perfect arbitrage prevents any price discrimination, partial arbitrage in the form of multiple or joint purchases may actually lead to more pronounced price discrimination than when consumers can only pick one single bundle. Further, clear predictions emerge for the price pattern, contrasting with the existing literature: with multiple purchases only, the firm offers strict quantity discounts; with joint purchase only, discounts are infeasible.

Family ties, incentives and development: A model of coerced altruism

We analyze the effects of family ties on the incentives for production of effort, where family ties are defined as a mixture of true and coerced altruism between family members. We model families as pairs of siblings. Each sibling exerts effort in order to obtain output under uncertainty. A social norm dictates that a sibling with a high output must share a specified amount of this output with his sibling, if the latters output is low. Siblings may be truly altruistic towards each other, but not to a larger degree than dictated by the social norm. We compare such informal family insurance with actuarially fair formal insurance. We show that coerced family altruism reduces individual efforts in equilibrium. However, individuals always benefit ex ante from living in families with coerced altruism, as compared with living in autarky. We show that a certain degree of coerced family altruism is robust as a social norm in a society of selfish individuals. Finally, we show that if family members are sufficiently altruistic to each other, then informal family insurance by way of coerced altruism may outperform actuarially fair insurance programs.

The Fetters of the Sib: Weber Meets Darwin

We analyze how family ties affect incentives, with focus on the strategic interaction between a pair of mutually altruistic siblings. Each sibling exerts effort to produce output under uncertainty and the siblings may transfer output to each other. With equally altruistic siblings, their equilibrium effort is nonmonotonic in the common degree of altruism and depends on the harshness of the environment. We define a notion of local evolutionary robustness of degrees of sibling altruism, and show that this degree is less than one half, the kinship relatedness factor. By way of numerical simulations we show that family ties are weaker in harsher environments.