Showing papers by "University of Chicago published in 1999"

Sexual dysfunction in the United States: prevalence and predictors.

Abstract: ContextWhile recent pharmacological advances have generated increased public interest and demand for clinical services regarding erectile dysfunction, epidemiologic data on sexual dysfunction are relatively scant for both women and men.ObjectiveTo assess the prevalence and risk of experiencing sexual dysfunction across various social groups and examine the determinants and health consequences of these disorders.DesignAnalysis of data from the National Health and Social Life Survey, a probability sample study of sexual behavior in a demographically representative, 1992 cohort of US adults.ParticipantsA national probability sample of 1749 women and 1410 men aged 18 to 59 years at the time of the survey.Main Outcome MeasuresRisk of experiencing sexual dysfunction as well as negative concomitant outcomes.ResultsSexual dysfunction is more prevalent for women (43%) than men (31%) and is associated with various demographic characteristics, including age and educational attainment. Women of different racial groups demonstrate different patterns of sexual dysfunction. Differences among men are not as marked but generally consistent with women. Experience of sexual dysfunction is more likely among women and men with poor physical and emotional health. Moreover, sexual dysfunction is highly associated with negative experiences in sexual relationships and overall well-being.ConclusionsThe results indicate that sexual dysfunction is an important public health concern, and emotional problems likely contribute to the experience of these problems.

The Provision of Incentives in Firms

Abstract: I NCENTIVES ARE the essence of economics. Despite many wide-ranging claims about their supposed importance, there has been little empirical assessment of incentive provision for workers. The purpose of this paper is to critically overview existing work on the provision of incentives. Since the interests of workers and their employers are not always aligned, a large theoretical literature has emphasized how firms design compensation contracts to induce employees to operate in the firm's interest. This literature has reached into many areas of compensation and has pointed to a multitude of different mechanisms that can be used to induce workers to act in the interests of their employers. These include piece rates, options, discretionary bonuses, promotions, profit sharing, efficiency wages, deferred compensation, and so on. My objective here is to evaluate this literature in the light of a growing empirical literature on compensation. Where possible, I will address the literature from two perspectives. First, an underlying assumption of this literature is that individuals respond to contracts that reward performance. Accordingly, I consider whether agents behave in this way, and whether these responses are always in the firm's interest. Second, I address whether firms write contracts with these responses in mind. In other words, do contracts look like the predictions of the theory? Incentives are provided to workers

The Economics and Econometrics of Active Labor Market Programs

Abstract: Policy makers view public sector-sponsored employment and training programs and other active labor market policies as tools for integrating the unemployed and economically disadvantaged into the work force. Few public sector programs have received such intensive scrutiny, and been subjected to so many different evaluation strategies. This chapter examines the impacts of active labor market policies, such as job training, job search assistance, and job subsidies, and the methods used to evaluate their effectiveness. Previous evaluations of policies in OECD countries indicate that these programs usually have at best a modest impact on participants’ labor market prospects. But at the same time, they also indicate that there is considerable heterogeneity in the impact of these programs. For some groups, a compelling case can be made that these policies generate high rates of return, while for other groups these policies have had no impact and may have been harmful. Our discussion of the methods used to evaluate these policies has more general interest. We believe that the same issues arise generally in the social sciences and are no easier to address elsewhere. As a result, a major focus of this chapter is on the methodological lessons learned from evaluating these programs. One of the most important of these lessons is that there is no inherent method of choice for conducting program evaluations. The choice between experimental and non-experimental methods or among alternative econometric estimators should be guided by the underlying economic models, the available data, and the questions being addressed. Too much emphasis has been placed on formulating alternative econometric methods for correcting for selection bias and too little given to the quality of the underlying data. Although it is expensive, obtaining better data is the only way to solve the evaluation problem in a convincing way. However, better data are not synonymous with social experiments. © 1999 Elsevier Science B.V. All rights reserved.

The meta-analysis of response ratios in experimental ecology

Abstract: Meta-analysis provides formal statistical techniques for summarizing the results of independent experiments and is increasingly being used in ecology. The response ratio (the ratio of mean outcome in the experimental group to that in the control group) and closely related measures of proportionate change are often used as measures of effect magnitude in ecology. Using these metrics for meta-analysis requires knowledge of their statistical properties, but these have not been previously derived. We give the approximate sampling distribution of the log response ratio, discuss why it is a particularly useful metric for many applications in ecology, and demonstrate how to use it in meta-analysis. The meta-analysis of response-ratio data is illustrated using experimental data on the effects of increased atmospheric CO2 on plant biomass responses.

Mental accounting matters

Abstract: Mental accounting is the set of cognitive operations used by individuals and households to organize, evaluate, and keep track of financial activities Making use of research on this topic over the past decade, this paper summarizes the current state of our knowledge about how people engage in mental accounting activities Three components of mental accounting receive the most attention This first captures how outcomes are perceived and experienced, and how decisions are made and subsequently evaluated The accounting system provides the inputs to be both ex ante and ex post cost–benefit analyses A second component of mental accounting involves the assignment of activities to specific accounts Both the sources and uses of funds are labeled in real as well as in mental accounting systems Expenditures are grouped into categories (housing, food, etc) and spending is sometimes constrained by implicit or explicit budgets The third component of mental accounting concerns the frequency with which accounts are evaluated and ‘choice bracketing’ Accounts can be balanced daily, weekly, yearly, and so on, and can be defined narrowly or broadly Each of the components of mental accounting violates the economic principle of fungibility As a result, mental accounting influences choice, that is, it matters Copyright © 1999 John Wiley & Sons, Ltd

Home Bias at Home: Local Equity Preference in Domestic Portfolios

Abstract: The strong bias in favor of domestic securities is a well-documented characteristic of international investment portfolios, yet we show that the preference for investing close to home also applies to portfolios of domestic stocks. Specifically, U.S. investment managers exhibit a strong preference for locally headquartered firms, particularly small, highly levered firms that produce nontraded goods. These results suggest that asymmetric information between local and nonlocal investors may drive the preference for geographically proximate investments, and the relation between investment proximity and firm size and leverage may shed light on several well-documented asset pricing anomalies.

Interorganizational Endorsements and the Performance of Entrepreneurial Ventures

Abstract: This paper investigates how the interorganizational networks of young companies affect their ability to acquire the resources necessary for survival and growth. We propose that, faced with great uncertainty about the quality of young companies, third parties rely on the prominence of the affiliates of those companies to make judgments about their quality and that young companies “endorsed” by prominent exchange partners will perform better than otherwise comparable ventures that lack prominent associates. Results of an empirical examination of the rate of initial public offering (IPO) and the market capitalization at IPO of the members of a large sample of venture-capital-backed biotechnology firms show that privately held biotech firms with prominent strategic alliance partners and organizational equity investors go to IPO faster and earn greater valuations at IPO than firms that lack such connections. We also empirically demonstrate that much of the benefit of having prominent affiliates stems from the ...

Infliximab for the treatment of fistulas in patients with Crohn's disease.

Abstract: Background Enterocutaneous fistulas are a serious complication of Crohn's disease and are difficult to treat. Infliximab, a chimeric monoclonal antibody to tumor necrosis factor alpha, has recently been developed as a treatment for Crohn's disease. We conducted a randomized, multicenter, double-blind, placebo-controlled trial of infliximab for the treatment of fistulas in patients with Crohn's disease. Methods The study included 94 adult patients who had draining abdominal or perianal fistulas of at least three months' duration as a complication of Crohn's disease. Patients were randomly assigned to receive one of three treatments: placebo (31 patients), 5 mg of infliximab per kilogram of body weight (31 patients), or 10 mg of infliximab per kilogram (32 patients); all three were to be administered intravenously at weeks 0, 2, and 6. The primary end point was a reduction of 50 percent or more from base line in the number of draining fistulas observed at two or more consecutive study visits. A secondary end point was the closure of all fistulas. Results Sixty-eight percent of the patients who received 5 mg of infliximab per kilogram and 56 percent of those who received 10 mg per kilogram achieved the primary end point, as compared with 26 percent of the patients in the placebo group (P=0.002 and P=0.02, respectively). In addition, 55 percent of the patients assigned to receive 5 mg of infliximab per kilogram and 38 percent of those assigned to 10 mg per kilogram had closure of all fistulas, as compared with 13 percent of the patients assigned to placebo (P=0.001 and P=0.04, respectively). The median length of time during which the fistulas remained closed was three months. More than 60 percent of patients in all the groups had adverse events. For patients treated with infliximab, the most common were headache, abscess, upper respiratory tract infection, and fatigue. Conclusions Infliximab is an efficacious treatment for fistulas in patients with Crohn's disease.

A Stress tensor for Anti-de Sitter gravity

Abstract: We propose a procedure for computing the boundary stress tensor associated with a gravitating system in asymptotically anti-de Sitter space. Our definition is free of ambiguities encountered by previous attempts, and correctly reproduces the masses and angular momenta of various spacetimes. Via the AdS/CFT correspondence, our classical result is interpretable as the expectation value of the stress tensor in a quantum conformal field theory. We demonstrate that the conformal anomalies in two and four dimensions are recovered. The two dimensional stress tensor transforms with a Schwarzian derivative and the expected central charge. We also find a nonzero ground state energy for global AdS5, and show that it exactly matches the Casimir energy of the dual super Yang–Mills theory on S 3×R.

Beyond Social Capital: Spatial Dynamics of Collective Efficacy for Children

Abstract: We propose a theoretical framework on the structural sources and spatially embedded nature of three mechanisms that produce collective efficacy for children. Using survey data collected in 1995 from 8,782 Chicago residents, we examine variations in intergenerational closure, reciprocal local exchange, and shared expectations for informal social control across 342 neighborhoods. Adjusting for respondents' attributes, we assess the effects of neighborhood characteristics measured in the 1990 census and the role of spatial interdependence. The results show that residential stability and concentrated affluence, more so than poverty and racial/ethnic composition, predict intergenerational closure and reciprocal exchange. Concentrated disadvantage, by contrast, is associated with sharply lower expectations for shared child control. The importance of spatial dynamics in generating collective efficacy for children is highlighted-proximity to areas high in closure, exchange, and control bestows an advantage above and beyond the structural characteristics of a given neighborhood. Moreover, spatial advantages are much more likely to accrue to white neighborhoods than to black neighborhoods

The Effects of Financial Incentives in Experiments: A Review and Capital-Labor-Production Framework

Abstract: We review 74 experiments with no, low, or high performance-based financial incentives. The modal result has no effect on mean performance (though variance is usually reduced by higher payment). Higher incentive does improve performance often, typically judgment tasks that are responsive to better effort. Incentives also reduce “presentation” effects (e.g., generosity and risk-seeking). Incentive effects are comparable to effects of other variables, particularly “cognitive capital” and task “production” demands, and interact with those variables, so a narrow-minded focus on incentives alone is misguided. We also note that no replicated study has made rationality violations disappear purely by raising incentives.

Estimating Log Models: To Transform or Not to Transform?

Abstract: Data on health care expenditures, length of stay, utilization of health services, consumption of unhealthy commodities, etc. are typically characterized by: (a) nonnegative outcomes; (b) nontrivial fractions of zero outcomes in the population (and sample); and (c) positively-skewed distributions of the nonzero realizations. Similar data structures are encountered in labor economics as well. This paper provides simulation-based evidence on the finite-sample behavior of two sets of estimators designed to look at the effect of a set of covariates x on the expected outcome, E(y|x), under a range of data problems encountered in every day practice: generalized linear models (GLM), a subset of which can simply be viewed as differentially weighted nonlinear least-squares estimators, and those derived from least-squares estimators for the ln(y). We consider the first- and second- order behavior of these candidate estimators under alternative assumptions on the data generating processes. Our results indicate that the choice of estimator for models of ln(E(x|y)) can have major implications for empirical results if the estimator is not designed to deal with the specific data generating mechanism. Garden-variety statistical problems - skewness, kurtosis, and heteroscedasticity - can lead to an appreciable bias for some estimators or appreciable losses in precision for others.

The Effect of Raloxifene on Risk of Breast Cancer in Postmenopausal Women: Results From the MORE Randomized Trial

Abstract: ContextRaloxifene hydrochloride is a selective estrogen receptor modulator that has antiestrogenic effects on breast and endometrial tissue and estrogenic effects on bone, lipid metabolism, and blood clotting.ObjectiveTo determine whether women taking raloxifene have a lower risk of invasive breast cancer.Design and SettingThe Multiple Outcomes of Raloxifene Evaluation (MORE), a multicenter, randomized, double-blind trial, in which women taking raloxifene or placebo were followed up for a median of 40 months (SD, 3 years), from 1994 through 1998, at 180 clinical centers composed of community settings and medical practices in 25 countries, mainly in the United States and Europe.ParticipantsA total of 7705 postmenopausal women, younger than 81 (mean age, 66.5) years, with osteoporosis, defined by the presence of vertebral fractures or a femoral neck or spine T-score of at least 2.5 SDs below the mean for young healthy women. Almost all participants (96%) were white. Women who had a history of breast cancer or who were taking estrogen were excluded.InterventionRaloxifene, 60 mg, 2 tablets daily; or raloxifene, 60 mg, 1 tablet daily and 1 placebo tablet; or 2 placebo tablets.Main Outcome MeasuresNew cases of breast cancer, confirmed by histopathology. Transvaginal ultrasonography was used to assess the endometrial effects of raloxifene in 1781 women. Deep vein thrombosis or pulmonary embolism were determined by chart review.ResultsThirteen cases of breast cancer were confirmed among the 5129 women assigned to raloxifene vs 27 among the 2576 women assigned to placebo (relative risk [RR], 0.24; 95% confidence interval [CI], 0.13-0.44; P<.001). To prevent 1 case of breast cancer, 126 women would need to be treated. Raloxifene decreased the risk of estrogen receptor–positive breast cancer by 90% (RR, 0.10; 95% CI, 0.04-0.24), but not estrogen receptor–negative invasive breast cancer (RR, 0.88; 95% CI, 0.26-3.0). Raloxifene increased the risk of venous thromboembolic disease (RR, 3.1; 95% CI, 1.5-6.2), but did not increase the risk of endometrial cancer (RR, 0.8; 95% CI, 0.2-2.7).ConclusionAmong postmenopausal women with osteoporosis, the risk of invasive breast cancer was decreased by 76% during 3 years of treatment with raloxifene.

Geochemical Consequences of Increased Atmospheric Carbon Dioxide on Coral Reefs

Abstract: A coral reef represents the net accumulation of calcium carbonate (CaCO3) produced by corals and other calcifying organisms. If calcification declines, then reef-building capacity also declines. Coral reef calcification depends on the saturation state of the carbonate mineral aragonite of surface waters. By the middle of the next century, an increased concentration of carbon dioxide will decrease the aragonite saturation state in the tropics by 30 percent and biogenic aragonite precipitation by 14 to 30 percent. Coral reefs are particularly threatened, because reef-building organisms secrete metastable forms of CaCO3, but the biogeochemical consequences on other calcifying marine ecosystems may be equally severe.

Managerial Decisions and Long-Term Stock Price Performance

Abstract: A rapidly growing literature claims to reject the semi-strong form of the efficient market hypothesis by producing large estimates of long-term abnormal stock price performance subsequent to major corporate events. We re-examine three large samples of major managerial decisions, namely acquisitions, equity issues, and equity repurchases, and find little evidence of reliable long-term abnormal stock price performance for the three samples. The analysis shows (a) cross-sectional dependence of abnormal returns leads to inflated test statistics and (b) estimates of abnormal performance are small, and largely limited to small stocks, after accounting for the known mis-pricings of the model used to generate the results.

Prevalence of impaired glucose tolerance and diabetes in women with polycystic ovary syndrome.

Abstract: OBJECTIVE: NIDDM occurs commonly among women with polycystic ovary syndrome (PCOS). The prevalence and natural history of its precursor, impaired glucose tolerance (IGT), is less well known. The objective of this study was to characterize the prevalence and incidence of glucose intolerance in a large cohort of women with well-characterized PCOS. RESEARCH DESIGN AND METHODS: A total of 122 women with clinical and hormonal evidence of PCOS were recruited from the Medicine, Endocrinology, Gynecology, and Pediatrics Clinics at the University of Chicago. All women had a standard oral glucose tolerance test (OGTT) with measurement of glucose and insulin levels. A subset of 25 women were subsequently restudied with the aim of characterizing the natural history of glucose tolerance in PCOS. RESULTS: Glucose tolerance was abnormal in 55 (45%) of the 122 women: 43 (35%) had IGT and 12 (10%) had NIDDM at the time of initial study. The women with NIDDM differed from those with normal glucose tolerance in that they had a 2.6-fold higher prevalence of first-degree relatives with NIDDM (83 vs. 31%, P

Cell membrane and nuclear estrogen receptors (ERs) originate from a single transcript: studies of ERalpha and ERbeta expressed in Chinese hamster ovary cells.

Abstract: The existence of a putative membrane estrogen receptor (ER) has been supported by studies accomplished over the past 20 yr. However, the origin and functions of this receptor are not well defined. To study the membrane receptor, we transiently transfected cDNAs for ERalpha or ERbeta into Chinese hamster ovary (CHO) cells. Transfection of ERalpha resulted in a single transcript by Northern blot, specific binding of labeled 17beta-estradiol (E2), and expression of ER in both nuclear and membrane cell fractions. Competitive binding studies in both compartments revealed near identical dissociation constants (K(d)S) of 0.283 and 0.287 nM, respectively, but the membrane receptor number was only 3% as great as the nuclear receptor density. Transfection of ERbeta3 also yielded a single transcript and nuclear and membrane receptors with respective Kd values of 1.23 and 1.14 nM; the membrane receptor number was only 2% compared with expressed nuclear receptors. Estradiol binding to CHO-ERalpha or CHO-ERbeta activated Galphaq and G(alpha)s proteins in the membrane and rapidly stimulated corresponding inositol phosphate production and adenylate cyclase activity. Binding by 17-beta-E2 to either expressed receptor comparably enhanced the nuclear incorporation of thymidine, critically dependent upon the activation of the mitogen-activated protein kinase, ERK (extracellular regulated kinase). In contrast, c-Jun N-terminal kinase activity was stimulated by 17-beta-E2 in ERbeta-expressing CHO, but was inhibited in CHO-ERalpha cells. In summary, membrane and nuclear ER can be derived from a single transcript and have near-identical affinities for 17-beta-E2, but there are considerably more nuclear than membrane receptors. This is also the first report that cells can express a membrane ERbeta. Both membrane ERs activate G proteins, ERK, and cell proliferation, but there is novel differential regulation of c-Jun kinase activity by ERbeta and ERalpha.

Occult economies and the violence of abstraction: notes from the South African postcolony

Abstract: Postcolonial South Africa, like other postrevolutionary societies, appears to have witnessed a dramatic rise in occult economies: in the deployment, real or imagined, of magical means for material ends. These embrace a wide range of phenomena, from "ritual murder," the sale of body parts, and the putative production of zombies to pyramid schemes and other financial scams. And they have led, in many places, to violent reactions against people accused of illicit accumulation. In the struggles that have ensued, the major lines of opposition have been not race or class but generation—mediated by gender. Why is all this occurring with such intensity, right now? An answer to the question, and to the more general problem of making sense of the enchantments of modernity, is sought in the encounter of rural South Africa with the contradictory effects of millennial capitalism and the culture of neoliberalism. This encounter, goes the argument, brings "the global" and "the local"— treated here as analytic constructs rather than explanatory terms or empirical realities—into a dialectical interplay. It also has implications for the practice of anthropology, challenging us to do ethnography on an "awkward" scale, on planes that transect the here and now, then and there,

Stock Market Overreactions to Bad News in Good Times: A Rational Expectations Equilibrium Model

Abstract: This article presents a dynamic, rational expectations equilibrium model of asset prices where the drift of fundamentals (dividends) shifts between two unobservable states at random times. I show that in equilibrium, investors’ willingness to hedge against changes in their own “uncertainty” on the true state makes stock prices overreact to bad news in good times and underreact to good news in bad times. I then show that this model is better able than conventional models with no regime shifts to explain features of stock returns, including volatility clustering, “leverage effects,” excess volatility, and time-varying expected returns.

'Ecometrics': Toward A Science of Assessing Ecological Settings, with Application to the Systematic Social Observation of Neighborhoods

Abstract: This paper considers the quantitative assessment of ecological settings such as neighborhoods and schools. Available administrative data typically provide useful but limited information on such settings. We demonstrate how more complete information can be reliably obtained from surveys and observational studies. Survey-based assessments are constructed by aggregating over multiple item responses of multiple informants within each setting. Item and rater inconsistency produce uncertainty about the setting being assessed, with definite implications for research design. Observation-based assessments also have a multilevel error structure. The paper describes measures constructed from interviews, direct observations, and videotapes of Chicago neighborhoods and illustrates an “ecometric” analysis—a study of bias and random error in neighborhood assessments. Using the observation data as an illustrative example, we present a three-level hierarchical statistical model that identifies sources of error in aggregat...

Globalisation as Reterritorialisation: The Re-scaling of Urban Governance in the European Union

Abstract: Summary. In the rapidly growing literatures on globalisation, many authors have emphasised the apparent disembedding of social relations from their local-territorial pre-conditions. However, such arguments neglect the relatively ® xed and immobile forms of territorial organisation upon which the current round of globalisation is premised, such as urban-regional agglomerations and territorial states. This article argues that processes of reterritorialisation‐ the recon® guration and re-scaling of forms of territorial organisation such as cities and states‐ constitute an intrinsic moment of the current round of globalisation. Globalisation is conceived here as a reterritorialisation of both socioeconomic and political-institutional spaces that unfolds simultaneously upon multiple, superimposed geographical scales. The territorial organisation of contemporary urban spaces and state institutions must be viewed at once as a

Statistical issues in ecological meta‐analyses

Abstract: Meta-analysis is the use of statistical methods to summarize research findings across studies. Special statistical methods are usually needed for meta-analysis, both because effect-size indexes are typically highly heteroscedastic and because it is desirable to be able to distinguish between-study variance from within-study sampling-error variance. We outline a number of considerations related to choosing methods for the meta-analysis of ecological data, including the choice of parametric vs. resampling methods, reasons for conducting weighted analyses where possible, and comparisons fixed vs. mixed models in categorical and regression-type analyses.

The screening and diagnosis of autistic spectrum disorders

Abstract: The Child Neurology Society and American Academy of Neurology recently proposed to formulate Practice Parameters for the Diagnosis and Evaluation of Autism for their memberships. This endeavor was expanded to include representatives from nine professional organizations and four parent organizations, with liaisons from the National Institutes of Health. This document was written by this multidisciplinary Consensus Panel after systematic analysis of over 2,500 relevant scientific articles in the literature. The Panel concluded that appropriate diagnosis of autism requires a dual-level approach: (a) routine developmental surveillance, and (b) diagnosis and evaluation of autism. Specific detailed recommendations for each level have been established in this document, which are intended to improve the rate of early suspicion and diagnosis of, and therefore early intervention for, autism.

Toward a Geography of Trade Costs

Abstract: What are the barriers that separate nations? While recent work provides intriguing clues, we have remarkably little concrete evidence as to the nature, size, and shape of barriers. This paper offers direct and indirect evidence on trade barriers, moving us toward a comprehensive geography of trade costs. There are three main contributions. One, we provide detailed data on freight rates for a number of importers. Rates vary substantially over exporters, and aggregate expenditures on freight are at the low end of the observed range. This suggests import choices are made so as to minimize transportation costs. Two, we estimate the technological relationship between freight rates and distance and use this to interpret the trade barriers equivalents of common trade barrier proxies taken from the literature. The calculation reveals implausibly large barriers. Three, we use a multi-sector model of trade to isolate channels through which trade barriers affect trade volumes. The model motivates an estimation technique that delivers direct estimates of substitution elasticities. This allows a complete characterization of the trade costs implied by trade flows and a partition of those costs into three components: explicitly measured costs (tariffs and freight), costs associated with common proxy variables, and costs that are implied but unmeasured. Acknowledgments: Thanks for the gracious provision of data go to Jon Haveman, Rob Feenstra, Azita Amjadi and the ALADI secretariat. Thanks for helpful suggestions on previous drafts go to seminar participants at the Universities of Chicago, Michigan, and Texas, Boston University, NBER and the 4th Annual EIIT Conference at Purdue University. Finally, Julia Grebelsky and Dawn Conner provided outstanding research assistance. This research was funded by a grant from the University of Chicago’s Graduate School of Business.