Paper # Author Title
We study theoretically and empirically how consumers in an individual private long-term health insurance market with front-loaded contracts respond to newly mandated portability requirements of their old-age provisions. To foster competition, effective 2009, German legislature made the portability of standardized old-age provisions mandatory. Our theoretical model predicts that the portability reform will increase internal plan switching. However, under plausible assumptions, it will not increase external insurer switching. Moreover, the portability reform will enable unhealthier enrollees to reoptimize their plans. We find confirmatory evidence for the theoretical predictions using claims panel data from a big private insurer. Download Paper
We analyze how the life settlement market - the secondary market for life insurance - may affect consumer welfare in a dynamic equilibrium model of life insurance with one-sided commitment and overconfident policyholders. As in Daily et al. (2008) and Fang and Kung (2010), policyholders may lapse their life insurance policies when they lose their bequest motives; but in our model the policyholders may underestimate their probability of losing their bequest motive, or be overconfident about their future mortality risks. For the case of overconfidence with respect to bequest motives, we show that in the absence of life settlement overconfident consumers may buy too much" reclassiffication risk insurance for later periods in the competitive equilibrium. In contrast, when consumers are overconfident about their future mortality rates in the sense that they put too high a subjective probability on the low-mortality state, the competitive equilibrium contract in the absence of life settlement exploits the consumer bias by offering them very high face amounts only in the low-mortality state. In both cases, life settlement market can impose a discipline on the extent to which overconfident consumers can be exploited by the primary insurers. We show that life settlement may increase the equilibrium consumer welfare of overconfident consumers when they are sufficiently vulnerable in the sense that they have a sufficiently large intertemporal elasticity of substitution of consumption. Download Paper
A large empirical literature found that the correlation between insurance purchase and ex post realization of risk is often statistically insignificant or negative. This is inconsistent with the predictions from the classic models of insurance a la Akerlof (1970), Pauly (1974) and Rothschild and Stiglitz (1976) where consumers have one-dimensional heterogeneity in their risk types. It is suggested that selection based on multidimensional private information, e.g., risk and risk preference types, may be able to explain the empirical findings. In this paper, we systematically investigate whether selection based on multidimensional private information in risk and risk preferences, can, under different market structures, result in a negative correlation in equilibrium between insurance coverage and ex post realization of risk. We show that if the insurance market is perfectly competitive, selection based on multidimensional private information does not result in negative correlation property in equilibrium, unless there is a sufficiently high loading factor. If the insurance market is monopolistic or imperfectly competitive, however, we show that it is possible to generate negative correlation property in equilibrium when risk and risk preference types are sufficiently negative dependent, a notion we formalize using the concept of copula. We also clarify the connections between some of the important concepts such as adverse/advantageous selection and positive/negative correlation property. Download Paper
Medicare over billing refers to the phenomenon that providers report more and/or higher-intensity service codes than actually delivered to receive higher Medicare reimbursement. We propose a novel and easy-to-implement approach to detect potential over billing based on the hours worked implied by the service codes physicians submit to Medicare. Using the Medicare Part B Fee-for-Service (FFS) Physician Utilization and Payment Data in 2012 and 2013 released by the Centers for Medicare and Medicaid Services (CMS), we first construct estimates for physicians' hours spent on Medicare Part B FFS beneficiaries. Despite our deliberately conservative estimation procedure, we find that about 2,300 physicians, or 3% of those with a significant fraction of Medicare Part B FFS services, have billed Medicare over 100 hours per week. We consider this implausibly long hours. As a benchmark, the maximum hours spent on Medicare patients by physicians in National Ambulatory Medical Care Survey data are 50 hours in a week. Interestingly, we also find suggestive evidence that the coding patterns of the flagged physicians seem to be responsive to financial incentives: within code clusters with different levels of service intensity, they tend to submit more higher intensity service codes than unflagged physicians; moreover, they are more likely to do so if the marginal revenue gain from submitting mid- or high-intensity codes is relatively high Download Paper
We present a dynamic structural model of subprime adjustable-rate mortgage (ARM) borrowers making payment decisions taking into account possible consequences of different degrees of delinquency from their lenders. We empirically implement the model using unique data sets that contain information on borrowers' mortgage payment history, their broad balance sheets, and lender responses. Our investigation of the factors that drive borrowers' decisions reveals that subprime ARMs are not all alike. For loans originated in 2004 and 2005, the interest rate resets associated with ARMs, as well as the housing and labor market conditions were not as important in borrowers' delinquency decisions as in their decisions to pay off their loans. For loans originated in 2006, interest rate resets, housing price declines, and worsening labor market conditions all contributed importantly to their high delinquency rates. Counterfactual policy simulations reveal that even if the Labor rate could be lowered to zero by aggressive traditional monetary policies, it would have a limited effect on reducing the delinquency rates. We find that automatic modification mortgage designs under which the monthly payment or the principal balance of the loans are automatically reduced when housing prices decline can be effective in reducing both delinquency and foreclosure. Importantly, we find that automatic modification mortgages with a cushion, under which the monthly payment or principal balance reductions are triggered only when housing price declines exceed a certain percentage may result in a Pareto improvement in that borrowers and lenders are both made better off than under the baseline, with a lower delinquency and foreclosure rates. Our counterfactual analysis also suggests that limited commitment power on the part of the lenders to loan modification policies may be an important reason for the relatively small rate of modifications observed during the housing crisis Download Paper
Rotating Savings and Credit Association (Rosca) is an important informal Financial institution in many parts of the world used by participants to share income risks. What is the role of Rosca when formal credit market is introduced? We develop a model in which risk-averse participants attempt to hedge against their private income shocks with access to both Rosca and the formal credit and investigate their interactions. Using the gap of the borrowing and saving interest rates as a measure of the imperfectness of the credit market, we compare three cases: (i) Rosca without credit market; (ii) Rosca with a perfect credit market; (iii) Rosca with an imperfect credit market. We show that a perfect credit market completely crowds out the role of Rosca. However, when credit market is present but imperfect, we show that Rosca and the formal credit market can complement each other in improving social welfare. Interestingly, we find that the social welfare in an environment with both Rosca and formal credit market does not necessarily increase monotonically as the imperfectness of the credit market converges to zero. Download Paper
We present and empirically implement an equilibrium labor market search model where risk averse workers facing medical expenditure shocks are matched with firms making health insurance coverage decisions. Our model delivers a rich set of predictions that can account for a wide variety of phenomenon observed in the data including the correlations among firm sizes, wages, health insurance offering rates, turnover rates and workers' health compositions. We estimate our model by Generalized Method of Moments using a combination of micro datasets including Survey of Income and Program Participation, Medical Expenditure Panel Survey and Robert Wood Johnson Foundation Employer Health Insurance Survey. We use our estimated model to evaluate the equilibrium impact of the 2010 Affordable Care Act (ACA) and find that it would reduce the uninsured rate among the workers in our estimation sample from about 22% in the pre-ACA benchmark economy to less than 4%. We also find that income-based premium subsidies for health insurance purchases from the exchange play an important role for the sustainability of the ACA; without the premium subsidies, the uninsured rate would be around 18%. In contrast, as long as premium subsidies and health insurance exchanges with community ratings stay intact, ACA without the individual mandate, or without the employer mandate, or without both mandates, could still succeed in reducing the uninsured rates to 7.34%, 4.63% and 9.22% respectively. Download Paper
Bidders’ risk attitudes have key implications for choices of revenue-maximizing auction formats. In ascending auctions, bid distributions do not provide information about risk preference. We infer risk attitudes using distributions of transaction prices and participation decisions in ascending auctions with entry costs. Nonparametric tests are proposed for two distinct scenarios: first, the expected entry cost can be consistently estimated from data; second, the data does not report entry costs but contains exogenous variations of potential competition and auction characteristics. In the first scenario, we exploit the fact that the risk premium required for entry - the difference between ex ante expected profits from entry and the certainty equivalent .is strictly positive if and only if bidders are risk averse. Our test is based on identification of bidders’ ex ante profits. In the second scenario, our test builds on the fact that risk attitudes affect how equilibrium entry probabilities vary with observed auction characteristics and potential competition. We also show identification of risk attitudes in a more general model of ascending auctions with selective entry, where bidders receive entry-stage signals that are correlated with private values. Download Paper
We present and empirically implement an equilibrium labor market search model where risk averse workers facing medical expenditure shocks are matched with firms making health insurance coverage decisions. Our model delivers a rich set of predictions that can account for a wide variety of phenomenon observed in the data including the correlations among firm sizes, wages, health insurance offering rates, turnover rates and workers' health compositions. We estimate our model by Generalized Method of Moments using a combination of micro data sources including Survey of Income and Program Participation (SIPP), Medical Expenditure Panel Survey (MEPS) and Robert Wood Johnson Foundation Employer Health Insurance Survey. We use our estimated model to evaluate the equilibrium impact of the 2010 Affordable Care Act (ACA) and find that it would reduce the uninsured rate among the workers in our estimation sample from 20.12% to 7.27%. We also examine a variety of alternative policies to understand the roles of different components of the ACA in contributing to these equilibrium changes. Interestingly, we find that the uninsured rate will be even lower (at 6.44%) if the employer mandate in the ACA is eliminated. Download Paper
We develop a model of a Parole Board contemplating whether to grant parole release to a prisoner who has finished serving their minimum sentence. The model implies a simple outcome test for racial prejudice robust to the inframarginality problem. Our test involves running simple regressions of whether a prisoner recidivates on the exposure time to the risk of recidivism and its square, using only the sample of prisoners who are granted parole release strictly between their minimum and maximum sentences and separately by race. If the coefficient estimates on the exposure time term differ by race, then there is evidence of racial prejudice against the racial group with the smaller coefficient estimate. We implement our test for prejudice using data from Pennsylvania from January 1996 to December 31, 2001. Although we find racial differences in time served, we find no evidence for racial prejudice on the part of the Parole Board based on our outcome test. Download Paper
Bidders’ risk attitudes have important implications for sellers seeking to maximize expected revenues. In ascending auctions, auction theory predicts bid distributions in Bayesian Nash equilibrium does not convey any information about bidders' risk preference. We propose a new approach for inference of bidders’ risk attitudes when they make endogenous participation decisions. Our approach is based on the idea that bidders' risk premium -the difference between ex ante expected profits from entry and the certainty equivalent - required for entry into the auction is strictly positive if and only if bidders are risk averse. We show bidders' expected profits from entry into auctions is nonparametrically recoverable, if a researcher observes the distribution of transaction prices, bidders' entry decisions and some noisy measures of entry costs. We propose a nonparametric test which attains the correct level asymptotically under the null of risk-neutrality, and is consistent under fixed alternatives. We provide Monte Carlo evidence of the finite sample performance of the test. We also establish identification of risk attitudes in more general auction models, where in the entry stage bidders receive signals that are correlated with private values to be drawn in the bidding stage. Download Paper
Previous research has shown that the reasons for lapsation have important implications regarding the effects of the emerging life settlement market on consumer welfare. We present and empirically implement a dynamic discrete choice model of life insurance decisions to assess the importance of various factors in explaining life insurance lapsations. In order to explain some key features in the data, our model incorporates serially correlated unobservable state variables which we deal with using posterior distributions of the unobservables simulated from Sequential Monte Carlo (SMC) method. We estimate the model using the life insurance holding information from the Health and Retirement Study (HRS) data. Counterfactual simulations using the estimates of our model suggest that a large fraction of life insurance lapsations are driven by i.i.d choice specific shocks, particularly when policyholders are relatively young. But as the remaining policyholders get older, the role of such i.i.d. shocks gets smaller, and more of their lapsations are driven either by income, health or bequest motive shocks. Income and health shocks are relatively more important than bequest motive shocks in explaining lapsations when policyholders are young, but as they age, the bequest motive shocks play a more important role. We also suggest the implications of these findings regarding the effects of the emerging life settlement market on consumer welfare. Download Paper
We propose and empirically implement a test for the presence of racial prejudice among emergency department (ED) physicians based on the bounceback rates of the patients who were discharged after receiving diagnostic tests during their initial ED visits. A bounceback is defined as a return to the ED within 72 hours of being initially discharged. Based on a plausible model of physician behavior, we show that differential bounceback rates across patients of different racial groups who are discharged after receiving diagnostic tests from their ED visits are informative of the racial prejudice of the physicians.  Applying the test to administrative data of ED visits from California and New Jersey, we do not find evidence of prejudice against black and Hispanic patients. Our finding suggests that, at least in the emergency department setting, taste based discrimination does not play an important role in the racial disparities in health care. Download Paper
We extend the semi-parametric estimation method for dynamic discrete choice models using Hotz and Miller’s (1993) conditional choice probability (CCP) approach to the setting where individuals may have hyperbolic discounting time preferences and may be naive about their time inconsistency. We illustrate the proposed estimation method with an empirical application of adult women’s decisions to undertake mammography to evaluate the importance of present bias and naivety in the under-utilization of this preventive health care. Our results show evidence for both present bias and naivety. Download Paper
We study the effect of the life settlement market on the structure of long term contracts offered by the primary market for life insurance, as well as the effect on consumer welfare, using a dynamic model of life insurance with one sided commitment and bequest-driven lapsation. We show that the presence of life settlement affects the extent as well as the form of dynamic reclassification risk insurance in the equilibrium of the primary insurance market, and that the settlement market generally leads to lower consumer welfare. We also examine the primary insurers response to the settlement market when they can offer enriched contracts by specifying optimally chosen cash surrender values (CSVs). Download Paper
We report results from a large randomized natural field experiment conducted in southwestern China in the context of insurance for sows. Our study sheds light on two important questions about microinsurance. First, how does access to formal insurance affect farmers' production decisions? Second, what explains the low takeup rate of formal insurance, despite substantial premium subsidy from the government? We find that providing access to formal insurance significantly increases farmers' tendency to raise sows. We argue that this finding also suggests that farmers are not previously insured efficiently through informal mechanisms. We also provide several pieces of evidence suggesting that trust, or lack thereof, for government-sponsored insurance products is a significant barrier for farmers' willingness to participate in the insurance program. Download Paper