Quality differentiation is especially important in the hospital industry, where the choices of Medicare patients are unaffected by prices. Unlike previous studies that use geographic market concentration to estimate hospital competitiveness, this article emphasizes the importance of quality differentiation in this spatially differentiated market. I estimate a random-coefficients discrete-choice model that predicts patient flow to different hospitals and find that demand responses to both distance and quality are substantial. The estimates suggest that patients do not substitute toward alternative hospitals in proportion to current market shares, implying that geographic market concentration is an inappropriate measure of hospital competitiveness.

Impediments to worker mobility serve to mitigate the attrition of healthy individuals from employer-sponsored insurance pools, thereby creating a de facto commitment mechanism that allows for more complete insurance of health risks than would be possible in the absence of such frictions. Using data on health insurance contracts obtained from the 1987 National Medical Expenditure Survey, we find that the quantity of insurance provided is positively related to the degree of worker commitment. These results illustrate the importance of commitment in the design of long-term contracts, and provide an additional rationale for the bundling of health insurance with employment.

Suppliers who are better informed than purchasers, such as physicians treating insured patients, often have discretion over what to provide. I show how, when the purchaser observes what is supplied but neither the recipient type nor the actual cost incurred, optimal provision differs from what would be efficient if the purchaser had full information, weather or not the supplier can extract informational rent. The analysis is applied to, among other things, data on tests for coronary artery disease and to Medicare diagnosis-related groups defined by the treatment given, not just the diagnosis, illustrating the biases in provision that result.

I examine Health Maintenance Organizations' (HMOs) voluntary disclosure of product quality, which is not as complete as unraveling theories predict. After controlling for cost and demand factors, I find that HMOs use voluntary disclosure to differentiate from competitors, with lower disclosure rates in highly competitive markets. These findings are consistent with product differentiation, but challenge the intuition that competition should lead to more provision of quality information.

Insurers can exploit the heterogeneity within risk-adjustment classes to select the good risks because they have more information than the regulator on the expected expenditures of individual insurees. To counteract this cream skimming, mixed systems combining capitation and cost-based payments have been adopted that do not, however, generally use the past expenditures of insurees as a risk adjuster. In this article, two symmetric insurers compete for clients by differentiating the quality of service offered to them according to some private information about their risk. In our setting it is always welfare improving to use prior expenditures as a risk adjuster.

This paper studies the urban land market in China in 2003-2007. In China, all urban land is owned by the state. Leasehold use rights for land for (re)development are sold by city governments and are a key source of city revenue. Leasehold sales are viewed as a major venue for corruption, prompting a number of reforms over the years. Reforms now require all leasehold rights be sold at public auction. There are two main types of auction: regular English auction and an unusual type which we call a "two stage auction". The latter type of auction seems more subject to corruption, and to side deals between potential bidders and the auctioneer. Absent corruption, theory suggests that two stage auctions would most likely maximize sales revenue for properties which are likely to have relatively few bidders, or are "cold", which would suggest negative selection on property unobservables into such auctions. However, if such auctions are more corruptible, that could involve positive selection as city officials divert hotter properties to a more corruptible auction form. The paper finds that, overall, sales prices are lower for two stage auctions, and there is strong evidence of positive selection. The price difference is explained primarily by the fact that two stage auctions typically have just one bidder, or no competition despite the vibrant land market in Chinese cities.

In many countries, pharmacies receive high regulated markups and are protected from competition through geographic entry restrictions. We develop an empirical entry model for pharmacies and physicians with two features: entry restrictions and strategic complementarities. We find that the entry restrictions have directly reduced the number of pharmacies by more than 50%, and also indirectly reduced the number of physicians by about 7%. A removal of the entry restrictions, combined with a reduction in the regulated markups, would generate a large shift in rents to consumers, without reducing the availability of pharmacies. The public interest motivation for the current regime therefore has no empirical support.

We call markets in which intermediaries sell networks of suppliers to consumers who are uncertain about their needs "option demand markets." In these markets, suppliers may grant the intermediaries discounts in order to be admitted to their networks. We derive a measure of each supplier's market power within the network; the measure is based on the additional ex ante expected utility consumers obtain from the supplier's inclusion. We empirically validate the WTP measure by considering managed care purchases of hospital services in the San Diego market. Finally, we present three applications, including an analysis of hospital mergers in San Diego.

We analyze admission and discharge decisions when hospitals become capacity constrained on high-demand days, and develop a test for discrimination that, under certain circumstances, does not require controls for differences across patient groups. On high-demand days, patients are discharged earlier than expected compared to those discharged on low-demand days. High demand creates no statistically significant differences in hospitals' admission behavior. Thus, hospitals appear to ration capacity by hastening discharges rather than by restricting admissions. We could not reject a null hypothesis of no discrimination against Medicaid patients in discharges

This article examined the physician-patient agency relationship in the context of the prescription drug market in Japan. In this market, physicians often both prescribe and dispense drugs and can pocket profits in so doing. A concern is that, due to the incentive created by the mark-up, physicians' prescription decisions may be distorted. Empirical results using anti-hypertensive drugs suggest that physicians' prescription choices are influenced by the mark-up. However, physicians are also sensitive to the patient's out-of-pocket costs. Overall, although the mark-up affects prescription choices, physicians appear more responsive to the patient's out-of-pocket costs than their own profits from mark-up.

Estimated responses to report cards may reflect learning about quality that would have occurred in their absence ("market-based learning"). Using panel data on Medicare HMOs, we examine the relationship between enrollment and quality before and after report cards were mailed to 40 million Medicare beneficiaries in 1999 and 2000. We find consumers learn from both public report cards and market-based sources, with the latter having a larger impact. Consumers are especially sensitive to both sources of information when the variance in HMO quality is greater. The effect of report cards is driven by beneficiaries' responses to consumer satisfaction scores.

Despite the popularity of pay-for-performance (P4P) among health policymakers and private insurers as a tool for improving quality of care, there is little empirical basis for its effectiveness. We use data from published performance reports of physician medical groups contracting with a large network HMO to compare clinical quality before and after the implementation of P4P, relative to a control group. We consider the effect of P4P on both rewarded and unrewarded dimensions of quality. In the end, we fail to find evidence that a large P4P initiative either resulted in major improvement in quality or notable disruption in care.

Most U.S. states have enacted JSL reform, the move from a regime of joint and several liability (JSL) that allows plaintiffs to claim full recovery from any one of multiple defendants to one where defendants are held liable only for the harm they cause. Contrary to previous theoretical work, we show that JSL reform can increase precaution by judgment proof agent by giving "deep pockets" an incentive to reduce their own liability by bringing judgment-proof agents into court. This result can help explain our empirical findings showing that JSL reform reduces death rates (and hence increase precaution) for many types of accidents. Together, these results highlight the role that litigation costs and judgment-proof agents play in the functioning of the American tort system.

Despite the importance of principal-agent models in the development of modern economic theory, there are few estimations of these models. I recover the estimates of a principal-agent model and obtain an approximation to the optimal contract. The results show that out-of-pocket payments follow a concave profile with respect to costs of treatment. I estimate the welfare loss due to moral hazard, taking into account income effects. I also propose a new measure of moral hazard based on the conditional correlation between contractible and noncontractible variables.

I use data from the University of California to empirically examine the role of social learning in employees' choices of health plans. The basic empirical strategy starts with the observation that if social learning is important, health plan selections should appear to be correlated across employees within the same department. Estimates of discrete choice models in which individuals' perceived payoffs are influenced by coworkers' decisions reveal a significant (but not dominant) social effect. The strength of the effect depends on factors such as the department's size or the employee's demographic distance from her coworkers. The estimated effects are present even when the model allows for unobserved, department-specific heterogeneity in employee preferences, so the results cannot be explained away by unobservable characteristics that are common to employees of the same department.

We examine competition in the hospital industry, in particular the effect of ownership type (for-profit, not-for-profit, government). We estimate a structural model of demand and pricing in the hospital industry in California, then use the estimates to simulate the effect of a merger. California hospitals in 1995 face an average price elasticity of demand of -4.85. Not-for-profit hospitals face less elastic demand and act as if they have lower marginal costs. Their prices are lower than those of for-profits, but markups are higher. We simulate the effects of the 1997 merger of two hospital chains. In San Luis Obispo County, where the merger creates a near monopoly, prices rise by up to 53%, and the predicted price increase would not be substantially smaller were the chains not-for-profit.

We investigate the effects of political activity on pharmaceutical prices, focusing on the health care reform period in the early 1990s.We characterize firms based on their vulnerability to future price regulation and find that the more vulnerable firms were more likely to take various actions to forestall regulation, most notably coordinating on a specific percentage price increase during 1993. Since moderating price increases could have averted regulation, the coordination appears to be the industry's response to a collective action problem.

We estimate the welfare associated with the Medicare HMO program, now known as Medicare+Choice (M+C). We find that the creation of the M+C program resulted in approximately $15.6 billion in consumer surplus and $52 billion in profits from 1993 to 2000 (in 2000 dollars). This program most likely generated significant net social welfare. However, we find that consumer surplus is geographically unevenly distributed. Prescription drug coverage accounts for approximately 45% of the estimated consumer surplus for 2000. Consumer surplus increases in the number of plans in a county, and most of the increase in welfare is due to increased premium competition.

We examine optimal individual and entity-level liability for negligence when expected accident costs depend on both the agent's level of expertise and the principal's level of authority. We consider these issues in the context of physician and managed care organization (MCO) liability for medical malpractice. Under current law, physicians generally are considered independent contractors and hence MCOs are not liable for negligent acts by physicians. We find that the practice of reviewing the medical decisions of physicians affects their incentives to take care, which in turn implies that it is efficient for MCOs to be held liable for the torts committed by their physicians.

Economic theorists have given little attention to health-related externalities, such as those involved in the spread of AIDS. One reason for this is the critical role played by psychological factors, such as fear of testing, in the continued spread of the disease. We develop a model of AIDS transmission that acknowledges this form of fear. In this context we design a mechanism that not only encourages testing but also slows the spread of the disease through voluntary transmission. Our larger agenda is to demonstrate the power of psychological incentives in the public health arena.

This article analyzes the potential for competition policy to affect welfare and investment in a network industry. When a network is split between competitors, each internalizes less network effects, but may still invest to steal customers. I structurally estimate consumers' utility from adopting and using mobile phones, with transaction data from nearly the entire Rwandan network. I simulate the equilibrium choices of consumers and network operators. Adding a competitor earlier could have reduced prices and increased incentives to invest in rural towers, increasing welfare by the equivalent of 1% of GDP. However, forcing free interconnection can lower incentives to invest.