The costs and benefits of noncompete agreements

Noncompete agreements are elements of workers' contracts that limit the worker's job mobility in the event of a job separation. In this dissertation, I address two major questions: first, why are noncompete agreements used, especially among workers earning low wages? Second, what are the ramifications of use of noncompete agreements, both for the firms using them and for the markets in which those firms exist? In the first chapter, co-authored with Matthew Johnson, I show that low wage workers sign noncompete agreements when their wages are constrained. I use a novel sample of owners of hair salons to empirically demonstrate that, when wage constraints are more binding due to a greater minimum wage or a greater labor supply, noncompete agreements are used more frequently. I show that use in this context may not maximize the firm's joint surplus, suggesting that policy interventions may be welfare-enhancing. In the second chapter, I generalize the theory of the first chapter, allowing for intertemporal changes in labor markets. I posit the existence of noncompete agreement cycles, which may explain recent trends in use among low wage employees. In a noncompete agreement cycle, workers who separate must exit the labor market. Low labor supply decreases use of noncompete agreements, allowing labor supply to increase and leading to use of noncompete agreements once again. I examine the costs and benefits of a policy prohibiting NCAs, analyzing such a policy's sensitivity to various parameters. In the final chapter, I consider the effects of noncompete agreements on the effort exertion of workers. If a worker is able to exert effort in order to increase the value of an asset, that worker may wish to spin off a new firm to leverage its value. The worker's current employer faces a tradeoff: a noncompete agreement induces the employee to stay but decreases the employee's incentive to exert effort. I show that, when the value of a spinoff is unknown ex ante, noncompete agreements may cause large ex post efficiency losses by limiting creation of highly profitable spinoffs

quantreg. nonpar: An R Package for performing nonparametric series quantile regression

The R package quantreg.nonpar implements nonparametric quantile regression methods to estimate and make inference on partially linear quantile models. quantreg.nonpar obtains point estimates of the conditional quantile function and its derivatives based on series approximations to the nonparametric part of the model. It also provides pointwise and uniform confidence intervals over a region of covariate values and/or quantile indices for the same functions using analytical and resampling methods. This paper serves as an introduction to the package and displays basic functionality of the functions contained within.https://arxiv.org/abs/1610.08329Published and Accepted manuscript versions

quantreg. nonpar: An R Package for performing nonparametric series quantile regression

The R package quantreg.nonpar implements nonparametric quantile regression methods to estimate and make inference on partially linear quantile models. quantreg.nonpar obtains point estimates of the conditional quantile function and its derivatives based on series approximations to the nonparametric part of the model. It also provides pointwise and uniform confidence intervals over a region of covariate values and/or quantile indices for the same functions using analytical and resampling methods. This paper serves as an introduction to the package and displays basic functionality of the functions contained within.https://arxiv.org/abs/1610.08329Published and Accepted manuscript versions

A generalized linear mixed model for longitudinal binary data with a marginal logit link function

Longitudinal studies of a binary outcome are common in the health, social, and behavioral sciences. In general, a feature of random effects logistic regression models for longitudinal binary data is that the marginal functional form, when integrated over the distribution of the random effects, is no longer of logistic form. Recently, Wang and Louis [Biometrika 90 (2003) 765--775] proposed a random intercept model in the clustered binary data setting where the marginal model has a logistic form. An acknowledged limitation of their model is that it allows only a single random effect that varies from cluster to cluster. In this paper we propose a modification of their model to handle longitudinal data, allowing separate, but correlated, random intercepts at each measurement occasion. The proposed model allows for a flexible correlation structure among the random intercepts, where the correlations can be interpreted in terms of Kendall's $\tau$. For example, the marginal correlations among the repeated binary outcomes can decline with increasing time separation, while the model retains the property of having matching conditional and marginal logit link functions. Finally, the proposed method is used to analyze data from a longitudinal study designed to monitor cardiac abnormalities in children born to HIV-infected women.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS390 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Access to essential technologies for safe childbirth: a survey of health workers in Africa and Asia

Background: The reliable availability of health technologies, defined as equipment, medicines, and consumable supplies, is essential to ensure successful childbirth practices proven to prevent avoidable maternal and newborn mortality. The majority of global maternal and newborn deaths take place in Africa and Asia, yet few data exist that describe the availability of childbirth-related health technologies in these regions. We conducted a cross-sectional survey of health workers in Africa and Asia in order to profile the availability of health technologies considered to be essential to providing safe childbirth care. Methods: Health workers in Africa and Asia were surveyed using a web-based questionnaire. A list of essential childbirth-related health technologies was drawn from World Health Organization guidelines for preventing and managing complications associated with the major causes of maternal and newborn mortality globally. Demographic data describing each birth center were obtained and health workers reported on the availability of essential childbirth-related health technologies at their centers. Comparison analyses were conducted using Rao-Scott chi-square test statistics. Results: Health workers from 124 birth centers in 26 African and 15 Asian countries participated. All facilities exhibited gaps in the availability of essential childbirth-related health technologies. Availability was significantly reduced in birth centers that had lower birth volumes and those from lower income countries. On average across all centers, health workers reported the availability of 18 of 23 essential childbirth-related health technologies (79%; 95% CI, 74%, 84%). Low-volume facilities suffered severe shortages; on average, these centers reported reliable availability of 13 of 23 technologies (55%; 95% CI, 39%, 71%). Conclusions: Substantial gaps exist in the availability of essential childbirth-related health technologies across health sector levels in Africa and Asia. Strategies that facilitate reliable access to vital health technologies in these regions are an urgent priority

Complexity-based measures inform tai chi’s impact on standing postural control in older adults with peripheral neuropathy

Background: Tai Chi training enhances physical function and may reduce falls in older adults with and without balance disorders, yet its effect on postural control as quantified by the magnitude or speed of center-of-pressure (COP) excursions beneath the feet is less clear. We hypothesized that COP metrics derived from complex systems theory may better capture the multi-component stimulus that Tai Chi has on the postural control system, as compared with traditional COP measures. Methods: We performed a secondary analysis of a pilot, non-controlled intervention study that examined the effects of Tai Chi on standing COP dynamics, plantar sensation, and physical function in 25 older adults with peripheral neuropathy. Tai Chi training was based on the Yang style and consisted of three, one-hour group sessions per week for 24 weeks. Standing postural control was assessed with a force platform at baseline, 6, 12, 18, and 24 weeks. The degree of COP complexity, as defined by the presence of fluctuations existing over multiple timescales, was calculated using multiscale entropy analysis. Traditional measures of COP speed and area were also calculated. Foot sole sensation, six-minute walk (6MW) and timed up-and-go (TUG) were also measured at each assessment. Results: Traditional measures of postural control did not change from baseline. The COP complexity index (mean±SD) increased from baseline (4.1±0.5) to week 6 (4.5±0.4), and from week 6 to week 24 (4.7±0.4) (p=0.02). Increases in COP complexity—from baseline to week 24—correlated with improvements in foot sole sensation (p=0.01), the 6MW (p=0.001) and TUG (p=0.01). Conclusions: Subjects of the Tai Chi program exhibited increased complexity of standing COP dynamics. These increases were associated with improved plantar sensation and physical function. Although more research is needed, results of this non-controlled pilot study suggest that complexity-based COP measures may inform the study of complex mind-body interventions, like Tai Chi, on postural control in those with peripheral neuropathy or other age-related balance disorders

A measure of partial association for generalized estimating equations

Abstract: In a regression setting, the partial correlation coefficient is often used as a measure of 'standardized' partial association between the outcome y and each of the covariates in In a linear regression model estimated using ordinary least squares, with y as the response, the estimated partial correlation coefficient between y and x k can be shown to be a monotone function, denoted f (z), of the Z-statistic for testing if the regression coefficient of x k is 0. When y is non-normal and the data are clustered so that y and x are obtained from each member of a cluster, generalized estimating equations are often used to estimate the regression parameters of the model for y given x. In this paper, when using generalized estimating equations, we propose using the above transformation f (z) of the GEE Z-statistic as a measure of partial association. Further, we also propose a coefficient of determination to measure the strength of association between the outcome variable and all of the covariates. To illustrate the method, we use a longitudinal study of the binary outcome heart toxicity from chemotherapy in children with leukaemia or sarcoma

Improving Quality of Care for Maternal and Newborn Health: Prospective Pilot Study of the WHO Safe Childbirth Checklist Program

Background: Most maternal deaths, intrapartum-related stillbirths, and newborn deaths in low income countries are preventable but simple, effective methods for improving safety in institutional births have not been devised. Checklist-based interventions aid management of complex or neglected tasks and have been shown to reduce harm in healthcare. We hypothesized that implementation of the WHO Safe Childbirth Checklist program, a novel childbirth safety program for institutional births incorporating a 29-item checklist, would increase delivery of essential childbirth practices linked with improved maternal and perinatal health outcomes. Methods and Findings A pilot, pre-post-intervention study was conducted in a sub-district level birth center in Karnataka, India between July and December 2010. We prospectively observed health workers that attended to women and newborns during 499 consecutively enrolled birth events and compared these with observed practices during 795 consecutively enrolled birth events after the introduction of the WHO Safe Childbirth Checklist program. Twenty-nine essential practices that target the major causes of childbirth-related mortality, such as hand hygiene and uterotonic administration, were evaluated. The primary end point was the average rate of successful delivery of essential childbirth practices by health workers. Delivery of essential childbirth-related care practices at each birth event increased from an average of 10 of 29 practices at baseline (95%CI 9.4, 10.1) to an average of 25 of 29 practices afterwards (95%CI 24.6, 25.3; p<0.001). There was significant improvement in the delivery of 28 out of 29 individual practices. No adverse outcomes relating to the intervention occurred. Study limitations are the pre-post design, potential Hawthorne effect, and focus on processes of care versus health outcomes. Conclusions: Introduction of the WHO Safe Childbirth Checklist program markedly improved delivery of essential safety practices by health workers. Future study will determine if this program can be implemented at scale and improve health outcomes.

Placement of an aortomonoiliac stent graft without femorofemoral revascularization in endovascular aneurysm repair: a case report

<p>Abstract</p> <p>Introduction</p> <p>Endovascular aortic repair, if technically feasible, is the treatment of choice for patients with a contained ruptured aortic aneurysm who are unfit for open surgery.</p> <p>Case presentation</p> <p>We report the case of an 80-year-old Caucasian man who presented with an unusually configured, symptomatic infrarenal aortic aneurysm. His aneurysm showed an erosion of the fourth lumbar vertebra and a severely arteriosclerotic pelvic axis. A high thigh amputation of his right leg had been performed 15 months previously. On his right side, occlusion of his external iliac artery, common femoral artery, and deep femoral artery had occurred. His aneurysm was treated by a left-sided aortomonoiliac stent graft without femorofemoral revascularization, resulting in occlusions of both internal iliac arteries. No ischemic symptoms appeared, although perfusion of his right side was maintained only over epigastric collaterals.</p> <p>Conclusions</p> <p>The placement of aortomonoiliac stent grafts for endovascular treatment of infrarenal aortic aneurysms without contralateral revascularization is a feasible treatment option in isolated cases. In this report, access problems and revascularization options in endovascular aneurysm repair are discussed.</p