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Category Archives: 2015

The Professor and the Coal Miner: The effect of socioeconomic and geographical factors on breast cancer diagnosis and survival outcome

By Shelley Chen

Previous studies reported that patients who live farther from cancer centers do not necessarily experience delayed cancer detection and shortened survival. However, the results are biased because of the incomplete observation of patient survival, which cannot be properly accounted for with the multivariable regression model. In this thesis, I isolated the effect of the breast cancer patient’s distance to a comprehensive cancer center on the stage of diagnosis and survival using the Cox Proportional Hazards model. I linked data from the Kentucky Surveillance, Epidemiology, and End Results 18, the Kentucky Life Tables, and the Kentucky Area Health Resource Files and identified 37654 patients diagnosed with breast cancer. I estimated the effect of distance on marginal probability of cancer mortality, controlling for non-cancer related death, socioeconomic status, and demographic factors in patients. After controlling for covariates, travel distance between the patient and the nearest comprehensive cancer center was statistically significantly on the breast cancer mortality probability, but not on the stage of diagnosis. In the Kentucky population, patients who were located farther from comprehensive cancer centers experience an increased marginal probability of mortality (proportional hazard = 1.004; 95% CI: 1). The linkage of SEER 18 and AHRF data provided more comprehensive information on the socioeconomic risk factors of cancer mortality than past study datasets. For the stage of diagnosis, a low physician to population ratio and high county-level Medicaid coverage were associated with more advanced stages of diagnosis. In turn, a more advanced stage of diagnosis, lower physician to population ratio, and identification as African American increased the marginal probabilities of mortality.

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Advisor: Charles Becker, Kent Kimbrough | JEL Codes: I1, I13, I14 | Tagged: Breast Cancer, Cancer Mortality, Health Outcomes, Inequality, Socioeconomic, Stage

  1. 000502 1.007311

Deterring Ineffcient Gambling in Risk-Taking Agents

By Ryan Westphal

This paper proposes a model describing the incentive issues faced by prin-
cipals and agents when the agent has limited liability and is capable of un-
dertaking unidentifiable, inefficient risky behavior. We propose a contract
structure by which the principal deters risk by deferring payment to the
agent until she reaches an absorbing steady-state in which promised equity
alone deters inefficient behavior. The paper discusses the effect of exogenous
parameters on the tradeoffs facing the principal as well as the implications
they have on the efficient choice of contract. We also outline extensions to
the model in which the principal has access to a costly monitoring technology
to identify inefficient risk taking. The theoretical results have implications
for real-world employment contracts and practices in financial firms such as
investment banks and private equity funds.

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Advisor: Curtis Taylor | JEL Codes: D82, D86, G32, L14 | Tagged: Contract Theory, Moral Hazard., Optimal Contracts, Risk Management

Medicare’s Prospective Payment System: Do Differences in the Reimbursement Rate Affect Quantity of Care Delivered and Hospital Billing Practices?

By Russell Hollis

When the government changes Medicare policy, payment structures often accommodate the change through lowering reimbursement rates. Changes in reimbursements raise the question of what effect changes have on patient care. Using data sets from the Center for Medicare and Medicaid Services, I examine the diagnosis of major replacement or reattachment of the lower extremity and how the length of stay for patients responds to changing reimbursement rates. I extend my investigation of price incentives to monitor fraudulent coding by hospitals. In a sample of over 470,000 patients in 2,696 hospitals for fiscal year 2012, I find that a 1% increase in reimbursement leads to a .007% increase in length of stay for DRG 470 (without complications) patients and a .057% percent increase for DRG 469 (with complications) patients. I then find that a 10% decrease in reimbursement for DRG 470 or one percent increase for DRG 469 leads to a .0011 increase in fraction of DRG 469 patients in a particular hospital. Lastly, I comment on these results, which point to the evidence of price incentives in quantity of care an the possibility of “upcoding”1.

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Advisor: Allan Collard-Wexler | JEL Codes: H50, H51, I11, I13, I18 | Tagged: Diagnosis Related Group, Length of Stay, Medicare, Reimbursement, “Upcoding”

Google Search Volume Index: Predicting Returns, Volatility and Trading Volume of Tech Stocks

By Rui Xu

This paper investigates the efficacy of using Google Search Volume Index (SVI), a publicly available tool Google provides via Google Trends, to predict stock movements within the tech sector. Relative changes in weekly search volume index are recorded from April 2004 to March 2015 and correlated with weekly returns, realized volatility and trading volume of 10 actively traded tech stocks. Correlations are drawn for three different time periods, each representing a different stage of the financial business cycle, to find out how Search Volume Index correlates with stock market movements in economic recessions and booms. Google SVI is found to be significantly and positively correlated with trading volume and weekly closing price across 2004 to 2015, and positively correlated with realized volatility from 2009-2015. There exists a positive correlation between weekly stock returns and SVI for half of the stocks sampled across all 3 periods. The regression model was a better fit before and during the recession, suggesting the possibility of stronger “herding” behavior during those periods than in recent years.

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Advisor: Edward Tower | JEL Codes: G1, G14, G17 | Tagged: Analysis, Information, market efficiency, Stock Returns

Understanding Financial Incentive Health Initiatives: The Impact of the Janani Suraksha Yojana Conditional Cash Transfer Program on Institutional Delivery Rates and Out-of- Pocket Health Expenditure

By Ritika Jain

Demand-side financing is a policy tool used by nations to incentivize utilization of public institutions, and India’s Janani Suraksha Yojana (JSY) is one of the largest such financial incentive programs in the world. The program pays eligible pregnant women to deliver their babies in health institutions partnered with the program. This paper studies the impact of the JSY on changes in mothers’ health-seeking behavior to deliver in-facility and on the out-of-pocket expenditure (OOPE) for delivery that they incur. Using data from the most recent wave of India’s District-Level Household Survey conducted in 2007-08, this paper finds that the overall introduction of the program in districts in India does not lead to significant changes in institutional delivery or out-ofpocket expenditure outcomes. Further analysis of subpopulations shows that marginalized populations are responsive to JSY introduction in their district with increased probability of delivering in-facility of 1.10 – 3.40 percentage points. Lastly, results show that receiving JSY payments leads to a 1.34 percentage point increase in the probability of incurring OOPE, but a 4.81 percent decrease in the amount of OOPE incurred. The JSY is helping to reduce overall out-of-pocket spending on deliveries. However, the majority of program benefits are not reaching poor pregnant women as the JSY aims, communicating the need for improvement in population targeting.

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Advisor: Alison Hagy, Kent Kimbrough, Manoj Mohanan | JEL Codes: C22, I12, I18 | Tagged: Conditional Cash Transfer, Demand-side Financing, Difference-in-difference-in-differences, Difference-in-differences, Healthcare Reform, Maternal Health

The Implications of Population Aging for Economic Growth a Regional Comparative Study

By Paige Muggeridge

I use a reduced form regression model to determine the extent to which population aging accounts for economic growth in each of the nine regions of the world. Predominantly, I build upon the research of Bloom et al. (2010), which is central to formulating my regression equation. I separate the difference between each region’s average growth rate from the world average growth rate into demographic and non-demographic effects using the estimated coefficients. The results suggest that more economically developed regions have potentially benefited from population aging, while less economically developed regions have not.

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Advisor: Craig Burnside | Tagged: Economic Growth, Economic Policy, Labor-force Participation, Life Expectancy, Population Aging, Retirement Age

The New Landscape of the NBA: The 2011 Collective Bargaining Agreement’s Impact on Competitive Balance and Players’ Salaries

By Nicholas Yam

The National Basketball Association (NBA) passed a new Collective Bargaining Agreement (CBA) in 2011 that introduced many changes to the structure of the league. The purpose of those changes was to improve competitive balance among the league, allowing smaller market teams to better compete with larger market teams. Many of the changes targeted the league’s salary cap and teams’ ability to pay players. This paper aims to determine whether competitive balance in the NBA improved under the 2011 CBA. The paper also determines which types of players’ salaries were affected the most. The results showed that competitive balance did not improve under the 2011 CBA. However, the results showed that higher performing players were paid proportionally more money than lower performing players following 2011 CBA.

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Advisor: Peter Arcidiacon | JEL Codes: Z2, Z20, Z22

Inflation Volatility and Economic Growth: A Disaggregated Analysis

By Nicholas Becker

Inflation volatility has been theorized to negatively affect real economic growth, but empirical analyses have returned somewhat mixed results. Constructing my own dataset of household group inflation rates by disaggregating and linking Consumer Expenditure Survey data with Consumer Price Index data, I analyze inflation volatility and economic growth from the ground-up. Calculating inflation volatility using a moving-window methodology, I find: 1) significant heterogeneity of inflation volatility across household groups; 2) a negative correlation between inflation volatility and economic growth from 2000-2012 for all household groups, with a stronger negative correlation at lower income levels; 3) a positive correlation between volatility and growth during expansions and a negative correlation between volatility and growth during recessions. Results suggest reducing inflation volatility and refining policymaking to account for the heterogeneity of inflation volatility could improve growth over the longrun. Further analysis is warranted.

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Advisor: Nir Jaimovich | JEL Codes: E31, E32, O40 | Tagged: Inflation, Economic Growth

How does being a Serial Creator affect Probability of Campaign Success on Kickstarter?

By Minn Khine

This paper seeks to address the issue of how being a serial creator impacts campaign success on Kickstarter. My hypothesis is that being a serial creator – someone who has created 2 or more projects on Kickstarter – has a positive effect on probability of campaign success but there are diminishing marginal returns to this effect. A regression analysis over a sample of over 187 thousand Kickstarter projects from its inception in 2008 until December 2014 yields the following findings, which supports my hypothesis. I found that being a serial creator does have a positive effect on campaign success but there is diminishing marginal returns to being a serial creator. Furthermore, number of updates, number of reward levels, having a video, number of backers, FB Shares, FB Friends, and Number of Projects Backed all have positive effects on campaign success. On the other hand, comments, funding goal, and duration have negative effects on campaign success. The effect of the Fed Fund Rate on campaign success is inconclusive. In terms of how project characteristics and creator characteristics affect first time creators and serial creators differently, I found that Updates, Video, FBShares, FBFriends, and Goal matter less as number of projects created increases, in other words, for serial creators who’ve gathered more project experience. On the other hand, Rewards, Backers, ProjectsBacked, Comments, and Duration matter more as number of projects created increases.

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Advisor: Edward Tower, Grace Kim | JEL Codes: G21, G24, L26 | Tagged: Crowdfunding, Kickstarter, Serial creator

Resource Adequacy and Energy-Only Market Design: Assessing The Impact of ERCOT’s Operating Reserve Demand Curve1

By Max Lipscomb

I examine the effect of an Operating Reserve Demand Curve (ORDC) which was recently implemented in Texas to assist power producers in recovering their fixed investment costs. I characterize and employ an economic plant dispatch model to examine the ORDC’s effects on representative natural gas plants in Texas, allowing me to determine whether or not the ORDC is likely to induce new capital deployment. I find that the ORDC’s positive effects are minimal and likely negated by the policy’s complexity, sending unclear signals to prospective investors. My results suggest that the policy itself is insufficient to incentivize the construction of new generation capacity in Texas’s electricity market.

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Advisor: James Roberts | JEL Codes: L9, L94, L97 | Tagged: Demand Curve, Electricity, Energy-only Operting Reserve, ERCOT Texas, Resource Adequacy, Utility Power

Questions?

Undergraduate Program Assistant
Jennifer Becker
dus_asst@econ.duke.edu

Director of the Honors Program
Michelle P. Connolly
michelle.connolly@duke.edu