Wharton Faculty Research
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PublicationUniform Collapsibility of Distribution Dependence Over a Nominal, Ordinal or Continuous Background(2006-02-01) Ma, Zongming; Xie, Xianchao; Geng, ZhiCox and Wermuth proposed that the partial derivative of the conditional distribution function of a random variable Y given another X is used for measuring association between two variables with arbitrary distributions. This paper shows the condition for collapsibility of the association measure. PublicationDesign is Everything?(2011-05-01) Ulrich, KarlThis essay attempts to demarcate the industrial practice of product design and situate it in the context of academic research. The term product design presents definitional challenges, as it is used in practice in different ways, and even varies in usage regionally. For this article, product design is “conceiving and giving form to goods and services that address needs.” The activity of product design can be thought of as comprising several key decisions. Because the decisions of product design do not map cleanly to any one academic discipline, the subject has not garnered enough attention in any one field to develop fully its own academic identity. Scholarly research in product design has often been cultivated by the emergence of a methodological paradigm. While several such paradigms are in use, several others offer substantial promise. PublicationDiscussion of Accounting Discretion, Corporate Governance, and Firm Performance(2008-01-01) Guay, Wayne RBowen, Ragjopal, and Venkatachalam (2008) explore whether managers, on average, use accounting discretion for reporting objectives that are in the interests of shareholders (e.g., signaling, tax minimization, etc.), or alternatively whether managers use discretion opportunistically in the presence of governance structures that allow greater discretion. The authors find that although accounting discretion is positively related to governance structures that allow managers greater discretion in decision-making, there is no evidence that the portion of accounting discretion related to governance structures is negatively associated with firm performance. In this discussion, I emphasize the importance of decision rights allocation within widely held corporations, and how this allocation naturally leads to cross-sectional variation in the degree of discretion afforded managers. In contrast to much of the existing governance literature, I argue that governance structures that allow managers greater discretion in making decisions do not necessarily imply weak/poor governance. For example, it is difficult to see why a firm that allocates the least possible decision-making rights to their board or executives is necessarily the firm with highest quality governance. I also discuss why the observed relation between accounting discretion and firm performance may be uninformative about whether accounting discretion is used for opportunistic purposes. If shareholders/boards thoughtfully select an appropriate amount of overall decision-making discretion to allow managers, it will be difficult to determine whether specific types of discretion are used opportunistically. PublicationAnesthesia and Post-mortem Interval Profoundly Influence the Regulatory Serine Phosphorylation of Glycogen Synthase Kinase-3 in Mouse Brain(2005-01-10) Li, Xiaohua; Friedman, Ari B; Roh, Myoung-Sun; Jope, Richard SGlycogen synthase kinase-3 (GSK3) is a crucial enzyme contributing to the regulation of neuronal structure, plasticity and survival, is implicated as a contributory factor in prevalent diseases such as Alzheimer’s disease and mood disorders and is regulated by a wide range of signaling systems and pharmacological agents. Therefore, factors regulating GSK3 in vivo are currently of much interest. GSK3 is inhibited by phosphorylation of serine-9 or serine-21 in GSK3β and GSK3α, respectively. This study found that accurate measurements of phospho-Ser-GSK3 in brain are confounded by a rapid post-mortem dephosphorylation, with ~90% dephosphorylation of both GSK3 isoforms occurring within 2 min post-mortem. Furthermore, three anesthetics, pentobarbital, halothane and chloral hydrate, each caused large in vivo increases in the serine phosphorylation of both GSK3β and GSK3α in several regions of mouse brain. Thus, studies of the phosphorylation state of GSK3 in brain, and perhaps in other tissues, need to take into account post-mortem changes and the effects of anesthetics and there is a direct correlation between anesthesia and high levels of serine-phosphorylated GSK3. PublicationBanking for the Poor: Evidence From India(2005-04-01) Burgess, Robin; Pande, Rohini; Wong, GraceState-led credit and savings programs have been implemented in numerous low income countries, but their success in reaching the poor remains widely debated. We report on research that exploits the policy features of the Indian social banking program to provide evidence on this issue. State-led branch expansion into rural unbanked locations reduced poverty across Indian states. In addition, the enforcement of directed bank lending requirements was associated with increased bank borrowing among the poor, in particular low caste and tribal groups. (JEL: O38, G28) PublicationThe Causal Effect of Malaria on Stunting: A Mendelian Randomization and Matching Approach(2013-10-01) Kang, Hyunseung; Kreuels, Benno; Adjei, Ohene; Krumkamp, Ralf; May, Jürgen; Small, DylanBackground Previous studies on the association of malaria and stunted growth delivered inconsistent results. These conflicting results may be due to different levels of confounding and to considerable difficulties in elucidating a causal relationship. Randomized experiments are impractical and previous observational studies have not fully controlled for potential confounding including nutritional deficiencies, breastfeeding habits, other infectious diseases and socioeconomic status. Methods This study aims to estimate the causal effect between malaria episodes and stunted growth by applying a combination of Mendelian randomization, using the sickle cell trait, and matching. We demonstrate the method on a cohort of children in the Ashanti Region, Ghana. Results We found that the risk of stunting increases by 0.32 (P-value: 0.004, 95% CI: 0.09, 1.0) for every malaria episode. The risk estimate based on Mendelian randomization substantially differs from the multiple regression estimate of 0.02 (P-value: 0.02, 95% CI: 0.003, 0.03). In addition, based on the sensitivity analysis, our results were reasonably insensitive to unmeasured confounders. Conclusions The method applied in this study indicates a causal relationship between malaria and stunting in young children in an area of high endemicity and demonstrates the usefulness of the sickle cell trait as an instrument for the analysis of conditions that might be causally related to malaria. PublicationThe Inevitability of Marketwide Underpricing of Mortgage Default Risk(2006-01-01) Pavlov, Andrey; Wachter, Susan MLenders are frequently accused of mispricing the put option embedded in nonrecourse lending. Prior research shows one lender's incentives to underprice. Here, we identify the conditions for a marketwide underpricing equilibrium. We demonstrate that, in a market with many players, given sufficient time, a race to the bottom and marketwide mispricing are inevitable. Underpricing occurs because bank managers and shareholders exploit mispriced deposit insurance. We show that the probability of the underpricing equilibrium increases with time since the previous market crash and that the more volatile the underlying asset market, the more likely it is subject to underpricing. PublicationDeterminants and Outcomes of Internet Banking Adoption(2011-02-01) Xue, Mei; Hitt, Lorin M; Chen, Pei-yuThis paper examines the drivers of adoption of Internet banking and the linkages among adoption drivers and outcomes (product acquisition, service activity, profitability, loyalty). We relate Internet banking adoption to customer demand for banking services, the availability of alternative channels, customers' efficiency in service coproduction (“customer efficiency”), and local Internet banking penetration. We find that customers who have greater transaction demand and higher efficiency, and reside in areas with a greater density of online banking adopters, are faster to adopt online banking after controlling for time, regional, and individual characteristics. Consistent with prior work, we find that customers significantly increase their banking activity, acquire more products, and perform more transactions. These changes in behavior are not associated with short-run increases in customer profitability, but customers who adopt online banking have a lower propensity to leave the bank. Building on these observations we also find that the adoption drivers are linked to the postadoption changes in behavior or profitability. Customers who live in areas with a high branch density or high Internet banking penetration increase their product acquisition and transaction activity more than Internet banking adopters in other regions. Efficient customers and those with high service demand show greater postadoption profitability. PublicationAlternative Securities Trading Systems: Tests and Regulatory Implications of the Adoption of Technology(1996) Clemons, Eric K; Weber, Bruce WReasons for the mixed reactions to today's electronic off-exchange trading systems are examined, and regulatory implications are explored. Information technology (IT) could provide more automated markets, which have lower costs. Yet for an electronic trading system to form a liquid and widely used market, a sufficient number of traders would need to make a transition away from established trading venues and to this alternative way of trading. This transition may not actually occur for a variety of reasons. Two tests are performed of the feasibility and the desirability of transitions to new markets. In the first test, traders in a series of economic experiments demonstrate an ability to make a transition and develop a critical mass of trading activity in a newly opened market. In the second test, simulation is used to compare the floor-based specialist auction in place in most U.S. stock exchanges today to a disintermediated alternative employing screen-based order matching. The results indicate that reducing the role of dealer-intermediaries can actually diminish important measures of market quality. Our findings suggest that the low trading volumes on many off-exchange systems do not result from traders' inability to break away from established trading floors. Rather, today's off-exchange trading systems are not uniformly superior to the trading mechanisms of traditional exchanges. Thus, regulatory actions favoring off-exchange trading systems are not warranted; but, improved designs for IT-based trading mechanisms are needed, and when these are available, they are likely to win significant trading volume from established exchanges. PublicationSelecting Competitive Tactics: Try a Strategy Map(1987) Olivia, Terrence A; Day, Diana L; DeSarbo, Wayne SWhen developing strategy, a manager considers how various tactics will affect short-term performance and broad strategic direction. The skilled manager keeps those factors in mind and, simultaneously, gauges what the competition is up to. The authors describe a mapping technique that will help managers to do just that. Not only does the technique provide an accessible measure of relative competitive standing, but it also allows managers to simulate tactical changes and analyze their probably impact on business performance.