Ian McCarthy

Department of Economics
Emory University
Rich Memorial Building, Room 319
Atlanta, GA 30322
Tel: 404/727-8808

E-Mail: EmailAddress: hidden: you can email any NBER-related person as first underscore last at nber dot org
NBER Program Affiliations: HE
NBER Affiliation: Faculty Research Fellow
Institutional Affiliation: Emory University

NBER Working Papers and Publications

April 2018Multimarket Contact in Health Insurance: Evidence from Medicare Advantage
with Haizhen Lin: w24486
Many industries, including health insurance, are characterized by a handful of large firms that compete in multiple geographic markets. Such overlap across markets, defined as multimarket contact (MMC), may facilitate tacit collusion and thus reduce the intensity of competition. We examine the effects of MMC on health insurance prices and quality using comprehensive data on the Medicare Advantage (MA) market from 2008 through 2015. Our estimation strategy exploits two plausibly exogenous changes to MMC: 1) a merger-induced change in MMC due to consolidations in other markets; and 2) reimbursement policy changes in which benchmark rates were increased in a subset of markets, encouraging additional entry into those markets and therefore affecting MMC even in markets otherwise unaffected by t...
February 2018Hospital Pricing and Public Payments
with Michael Darden, Eric Barrette: w24304
A longstanding debate in health economics and health policy concerns how hospitals adjust prices with private insurers following reductions in public funding. A common argument is that hospitals engage in some degree of "cost-shifting," wherein hospitals increase prices with private insurers in response to a reduction in public payments; however, evidence of significant cost-shifting is mixed, and the rationale for such behavior is unclear. We enter this debate by examining plausibly exogenous variation in Medicare payment rates generated by two policies under the Affordable Care Act: the Hospital Readmission Reduction Program (HRRP) and the Hospital Value Based Purchasing (HVBP) program. We merge rich hospital-level information to actual private-payer payment data from a large, multi-pa...
July 2017It's a Cruel Summer: Household Responses to Reductions in Government Nutrition Assistance
with Lorenzo Almada: w23633
The appropriate size and scope of government nutrition assistance programs is a regular source of debate among policy-makers, and with calls to reduce government benefits, a clear understanding of household responses to any proposed benefit reduction is critical. Exploiting the design of U.S. nutrition assistance programs, we examine how low-income households reallocate their budgets following an exogenous reduction in nutrition assistance benefits. The magnitude of our results suggests that the budget for an average low-income household with children is severely inflexible and likely unable to absorb more than a $2 to $3 reduction in nutrition benefits per child per week.

Published: Lorenzo Almada & Ian M. McCarthy, 2017. "It's a Cruel Summer: Household Responses to Reductions in Government Nutrition Assistance," Journal of Economic Behavior & Organization, . citation courtesy of

September 2015What Can We Learn About the Effects of Food Stamps on Obesity in the Presence of Misreporting?
with Lorenzo Almada, Rusty Tchernis: w21596
There is an increasing perception among policy makers that food stamp benefits contribute positively to adult obesity rates. We show that these results are heavily dependent on one's assumptions regarding the accuracy of reported food stamp participation. When allowing for misreporting, we find no evidence that SNAP participation significantly increases the probability of being obese or overweight among adults. Our results also highlight the inherent bias and inconsistency of common point estimates when ignoring misreporting, with treatment effects from instrumental variable methods exceeding the non-parametric upper bounds by over 200% in some cases.

Published: Lorenzo Almada & Ian McCarthy & Rusty Tchernis, 2016. "What Can We Learn about the Effects of Food Stamps on Obesity in the Presence of Misreporting?," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 98(4), pages 997-1017. citation courtesy of

NBER Videos

National Bureau of Economic Research, 1050 Massachusetts Ave., Cambridge, MA 02138; 617-868-3900; email:

Contact Us