The analysis of incomplete data using stochastic covariates

In the development of many diseases there are often associated random variables which continuously reflect the progress of a subject towards the final expression of the disease (failure). At any given time these processes, which we call stochastic covariates, may provide information about the current hazard and the remaining time to failure. Likewise, in situations when the specific times of key prior events are not known, such as the time of onset of an occult tumour or the time of infection with HIV-1, it may be possible to identify a stochastic covariate which reveals, indirectly, when the event of interest occurred. The analysis of carcinogenicity trials which involve occult tumours is usually based on the time of death or sacrifice and an indicator of tumour presence for each animal in the experiment. However, the size of an occult tumour observed at the endpoint represents data concerning tumour development which may convey additional information concerning both the tumour incidence rate and the rate of death to which tumour-bearing animals are subject. We develop a stochastic model for tumour growth and suggest different ways in which the effect of this growth on the hazard of failure might be modelled. Using a combined model for tumour growth and additive competing risks of death, we show that if this tumour size information is used, assumptions concerning tumour lethality, the context of observation or multiple sacrifice times are no longer necessary in order to estimate the tumour incidence rate. Parametric estimation based on the method of maximum likelihood is outlined and is applied to simulated data from the combined model. The results of this limited study confirm that use of the stochastic covariate tumour size results in more precise estimation of the incidence rate for occult tumours.     

Joint tests of non-nested models and general error specifications

This paper is concerned with joint tests of non-nested models and simultaneous departures from homoskedasticity, serial independence and normality of the disturbance terms. Locally equivalent alternative models are used to construct joint tests since they provide a convenient way to incorporate more than one type of departure from the classical conditions. The joint tests represent a simple asymptotic solution to the “pre-testing” problem in the context of non-nested linear regression models. Our simulation results indicate that the proposed tests have good finite sample properties.     

Disruption in Parental Co-habitation and its Effects on Short-Term,Medium-Term,and Long-Term Outcomes of Adolescents

In this paper the relationships between a disruption in parental co-habitation and various categories of adolescent outcomes over multiple time horizons are explored. Using data from the National Longitudinal Study of Adolescent Health (Add Health), we estimated the effects of a change from living with both parents to just one, on academic and employment outcomes, the likelihood to indulge in risky behaviors, mental health outcomes and body mass index measures, from less than 1 year to over 14 years after the change. Propensity score matching methods were used to control for individual characteristics and pre-existing differences in the family environment that may increase the chances of separation, and the results are compared to those obtained using ordinary least squares or probit methods. Results showed evidence of adverse effects of living with one parent in the short term, medium term and long term. Adolescents living with one parent had lower academic achievement in all term lengths, poor mental health in the short to medium term, and were more likely to engage in risky behaviors in the medium to long term.     

Women in Upper Echelons of Management,Tenure and Legal Risk

Integrating risk, gender diversity and upper echelons literatures, we examine whether the presence of women in upper management (top management team (TMT) and board of directors (BOD)) and the tenure of TMTs and BODs are associated with the risk of lawsuits. An analysis of data from firms in the US retail industry shows that the presence of women in TMTs and BODs and the tenure of TMTs and BODs are negatively associated with legal risk, but longer tenured BODs with more women had a positive impact on lawsuits. Implications and suggestions for future research are offered.     

CONTESTS WITH DRAWS: AXIOMATIZATION AND EQUILIBRIUM

We introduce and axiomatize a class of single‐winner contest success functions that embody the possibility of a draw. We then analyze the game of contest that our success functions induce, having different prizes delivered in the occurrence of a win and a draw. We identify conditions for the existence and uniqueness of a symmetric interior Nash equilibrium and show that equilibrium efforts and equilibrium rent dissipation can be larger than in a Tullock contest (with no possibility of a draw) due to increased competition even if the draw‐prize is null. These results suggest that a contest designer may profit from introducing the possibility of a draw. Finally, we show that this approach naturally extends to multiprize contests with multiple draws across different subsets of the set of players. (JEL C72, D72, D74)     

Supply Chain Consequences of Subsidies for Corporate Social Responsibility

The use of government incentives tied to market prices as means of boosting corporate social responsibility (CSR) has expanded notably in recent decades. Enhanced business tax deductions for charitable donations and credits for conservation easements are notable cases. While providing incentives for socially desirable behavior to achieve legislative goals has intuitive appeal, the broader economic consequences are not always fully understood. In this study, we examine such wider consequences for supply chains when subsidies for CSR are offered. One effect we identify is that since incentives are typically tied to market value, firms have not only an added incentive to achieve societal objectives (say by donating inventory) but also an incentive to raise output (retail) market prices. A second consequence is that since firms forgo potential revenues by engaging in socially desired behavior, they become increasingly sensitive to supplier pricing; in an uncoordinated supply chain this leads to input (wholesale) price concessions. Among other things, the results underscore that incentives put in place to meet broader societal objectives also have notable ramifications for suppliers, retailers, and consumers in primary markets.     

On some consistent tests of mutual independence among several random vectors of arbitrary dimensions

Statistics and Computing - Testing for mutual independence among several random vectors is a challenging problem, and in recent years, it has gained significant attention in statistics and machine...     

Gendering Global Governance

In this article I map out the major debates on global governance and the feminist critiques of the mainstream interventions in these debates. I argue that the shift from government to governance is a response to the needs of a gendered global capitalist economy and is shaped by struggles, both discursive and material, against the unfolding consequences of globalization. I suggest feminist interrogations of the concept, processes, practices and mechanisms of governance and the insights that develop from them should be centrally incorporated into critical revisionist and radical discourses of and against the concept of global governance. However, I also examine the challenges that the concept of global governance poses for feminist political practice, which are both of scholarship and of activism as feminists struggle to address the possibilities and politics of alternatives to the current regimes of governance. I conclude by suggesting that feminist political practice needs to focus on the politics of redistribution in the context of global governance.     

Preventing workplace aggression and violence--a role for occupational therapy

Workplace aggression and violence is the fastest growing societal concerns in USA. The review of literature indicates that violence is a substantial contributor to occupational injuries and death. Preventative strategies for minimizing the risk of workplace violence include, cash-handling policies, physical separation of workers from customers, environmental modifications; good lighting, security devices, escort services, and employee training. Studies also suggest that as a preventive measure, employers will attract and retain the best workers if high-risk behaviors are discouraged and appropriate behaviors are supported. Proactive strategies reduce stress, increase productivity, and enhance creativity. A role for occupational therapy practitioners in the prevention of workplace violence is proposed.