Adam Hale Shapiro

Does Competition Reduce Price Dispersion? New Evidence from the Airline Industry

We analyze the effects of competition on price dispersion in the airline industry, using panel data from 1993:Q1 through 2006:Q3. Competition has a negative effect on price dispersion, in line with the textbook treatment of price discrimination. This effect is pronounced for routes with consumers characterized by relatively heterogeneous elasticities of demand. On routes with a homogeneous customer base, the effects of competition on price dispersion are smaller. Our results contrast with those of Borenstein and Rose, who found that price dispersion increases with competition. We reconcile the different results by showing that the cross‐sectional estimator suffers from omitted‐variable bias.

Subprime Outcomes: Risky Mortgages, Homeownership Experiences, and Foreclosures

This paper provides the first rigorous assessment of the homeownership experiences of subprime borrowers. We consider homeowners who used subprime mortgages to buy their homes, and estimate how often these borrowers end up in foreclosure. In order to evaluate these issues, we analyze homeownership experiences in Massachusetts over the 1989-2007 period using a competing risks, proportional hazard framework. We present two main findings. First, homeownerships that begin with a subprime purchase mortgage end up in foreclosure almost 20 percent of the time, or more than 6 times as often as experiences that begin with prime purchase mortgages. Second, house price appreciation plays an important role in generating foreclosures. In fact, we attribute much of the dramatic rise in Massachusetts foreclosures during 2006 and 2007 to the decline in house prices that began in the summer of 2005.

Do Physicians Possess Market Power

We study the degree to which greater physician concentration leads to higher service prices charged by physicians in the commercially insured medical care market. Using a database of physicians throughout the United States, we construct physician-firm concentration measures based on market boundaries defined by fixed driving times, which we label the fixed-travel-time Herfindahl-Hirschman index. We link these concentration measures to health insurance claims. We find that physicians in more concentrated markets charge higher service prices; a physician in the 90th percentile of market concentration will charge 14–30 percent higher fees than a physician in the 10th percentile. Our estimates imply that physician consolidation has caused about an 8 percent increase in fees on average over the last 20 years and substantially higher increases in concentrated markets.

Decomposing the Foreclosure Crisis: House Price Depreciation versus Bad Underwriting

We estimate a model of foreclosure using a data set that includes every residential mortgage, purchase-and-sale, and foreclosure transaction in Massachusetts from 1989 to 2008. We address the identification issues related to the estimation of the effects of house prices on residential foreclosures. We then use the model to study the dramatic increase in foreclosures that occurred in Massachusetts between 2005 and 2008 and conclude that the foreclosure crisis was primarily driven by the severe decline in housing prices that began in the latter part of 2005, not by a relaxation of underwriting standards on which much of the prevailing literature has focused. We argue that relaxed underwriting standards did severely aggravate the crisis by creating a class of homeowners who were particularly vulnerable to the decline in prices. But, as we show in our counterfactual analysis, that emergence alone, in the absence of a price collapse, would not have resulted in the substantial foreclosure boom that was experienced.

Medical Care Price Indexes for Patients with Employer-Provided Insurance: Nationally Representative Estimates from MarketScan Data

OBJECTIVE Commonly observed shifts in the utilization of medical care services to treat diseases may pose problems for official price indexes at the Bureau of Labor Statistics (BLS) that do not account for service shifts. We examine how these shifts may lead to different price estimates than those observed in official price statistics at the BLS. DATA SOURCES We use a convenience sample of enrollees with employer-provided insurance from the MarketScan database for the years 2003 to 2007. Population weights that consider the age, sex, and geographic distribution of enrollees are assigned to construct representative estimates. STUDY DESIGN We compare two types of price indexes: (1) a Service Price Index (SPI) that is similar to the BLS index, which holds services fixed and measures the prices of the underlying treatments; (2) a Medical Care Expenditure Index (MCE) that measures the cost of treating diseases and allows for utilization shifts. PRINCIPAL FINDINGS Over the entire period of study the CAGR of the SPI grows 0.7 percentage points faster than the preferred MCE index. CONCLUSIONS Our findings suggest that the health component of inflation may be overstated by 0.7 percentage points per year, and real GDP growth may be understated by a similar amount. However, more work may be necessary to precisely replicate the indexes of the BLS to obtain a more accurate measure of these price differences.

Geographic variation in commercial medical-care expenditures: A framework for decomposing price and utilization

This study introduces a new framework for measuring and analyzing medical-care expenditures. The framework focuses on expenditures at the disease level that are decomposed between price and utilization. We find that both price and utilization differences are important contributors to expenditure differences across commercial markets. Further examination shows that for some diseases utilization drives variation while for others price is more important. Finally, when disease-specific measures are aggregated across diseases, much of the important disease-specific variation is masked, leading to much smaller measures of aggregate variation.

The Effects of Competition on Price Dispersion in the Airline Industry: A Panel Analysis

This paper analyzes the effects of market structure on price dispersion in the airline industry, using panel data from 1993 through 2006. The results found in this paper contrast with those of Borenstein and Rose (1994), who found that price dispersion increases with competition. We find that competition has a negative effect on price dispersion, in line with the textbook treatment of price discrimination. Specifically, the effects of competition on price dispersion are most significant on routes that we identify as having consumers characterized by relatively heterogeneous elasticities of demand. On routes with a more homogenous customer base, the effects of competition on price discrimination are largely insignificant. We conclude from these results that competition acts to erode the ability of a carrier to price discriminate, resulting in reduced overall price dispersion.

Physician payments under health care reform

This study examines the impact of major health insurance reform on payments made in the health care sector. We study the prices of services paid to physicians in the privately insured market during the Massachusetts health care reform. The reform increased the number of insured individuals as well as introduced an online marketplace where insurers compete. We estimate that, over the reform period, physician payments increased at least 11 percentage points relative to control areas. Payment increases began around the time legislation passed the House and Senate-the period in which their was a high probability of the bill eventually becoming law. This result is consistent with fixed-duration payment contracts being negotiated in anticipation of future demand and competition.

Decomposing Medical-Care Expenditure Growth

Medical-care expenditures have been rising rapidly, accounting for over 17 percent of GDP in 2012. In this study, we assess the sources of the rising medical-care expenditures in the commercial sector. We employ a novel framework for decomposing expenditure growth into four components at the disease level: service price growth, service utilization growth, treated disease prevalence growth, and demographic shift. The decomposition shows that growth in prices and treated prevalence are the primary drivers of medical-care expenditure growth over the 2003 to 2007 period. There was no growth in service utilization at the aggregate level over this period. Price and utilization growth were especially large for the treatment of malignant neoplasms. For many conditions, treated prevalence has shifted towards preventive treatment and away from treatment for late-stage illnesses.

The Impact of Competition on Technology Adoption: An Apples-to-PCs Analysis

We study the effect of market structure on a personal computer manufacturer’s decision to adopt new technology. This industry is unusual because there exist two horizontally segmented retail markets with different degrees of competition: the IBM-compatible (or PC) platform and the Apple platform. We first document that, relative to Apple, producers of PCs typically have more frequent technology adoption, shorter product cycles, and steeper price declines over the product cycle. We then develop a parsimonious vintage-capital model that matches the prices and sales of PC and Apple products. The model predicts that competition is the key driver of the rate at which technology is adopted.