Sensitivity of Physiologically Based Pharmacokinetic Models to Variation in Model Parameters: Methylene Chloride

The parameters in a physiologically based pharmacokinetic (PBPK) model of methylene chloride were varied systematically, and the resulting variation in a number of model outputs was determined as a function of time for mice and humans at several exposure concentrations. The importance of the various parameters in the model was highly dependent on the conditions (concentration, species) for which the simulation was performed and the model output (dose surrogate) being considered. Model structure also had a significant impact on the results. For sensitivity analysis, particular attention must be paid to conservation equations to ensure that the variational calculations do not alter mass balance, introducing extraneous effects into the model. All of the normalized sensitivity coefficients calculated in this study ranged between −1.12 and 1, and most were much less than 1 in absolute value, indicating that individual input errors are not greatly amplified in the outputs. In addition to ranking parameters in terms of their impact on model predictions, time-dependent sensitivity analysis can also be used as an aid in the design of experiments to estimate parameters by predicting the experimental conditions and sampling points which will maximize parameter identifiability.     

Industrial Origin of CEOs in Outside Succession: Board Preference and Stockholder Reaction

Although scholars have studied outside executive succession for decades, there is still no clear definition of the term outsider. We focus on a new dimension of outsiderness, the industrial background of executives hired from outside the firm into a CEO position. This paper examines the antecedents of boards' decisions on the industry origin of outside successors as well as the short-term stock market response. We find that firms with more independent boards and with blockholders owning large amounts of stock are more likely to hire industry unrelated successors. However, the board's decision does not strictly follow the rhetoric of stockholder's interests. The stock market reacts more positively to outside CEO succession announcements when the CEO comes from an industry related firm. These findings support our theoretical arguments that the boards of directors may use a logic or rule of appropriateness in deciding the industrial origin of outside successors.     

MALE MARITAL WAGE DIFFERENTIALS: TRAINING,PERSONAL CHARACTERISTICS,AND FIXED EFFECTS

Using the National Longitudinal Survey of Youth 1979, we replicate previous estimates of the marital wage differential for white men, extend the analysis to African American men, then explain the within and between race differentials. We first control for formal job training, then for cognitive skills, parental background, and self‐esteem with little effect. By contrast, the white differential but not the black differential disappears in fixed‐effects estimation. We reconcile the cross‐section/panel differentials by focusing on the distinct identification conditions employed by each technique. Men who never change marital status play a significant role in white cross‐sectional estimates. (JEL J31, J12)     

The Status of Sociology within the Academy: Where We Are, Why We’re There, and How to Change It

We present data from a survey of deans at colleges and universities throughout the USA on the relative status of disciplines. Findings indicate that the relative status of Sociology within the academy is low, although there are several specific areas of high status—namely, concerning community involvement and engagement. Our analyses also investigate which areas of activity are most closely associated with the overall prestige of disciplines. Findings indicate that research-oriented activities are the most influential, while student-oriented activities have a more ambivalent association with status. Based on those findings, we offer suggestions for raising the status of the discipline, based on the cultivation of natural synergies linking research, community engagement, student training, and focusing on the benefits of establishing social science research centers associated with Sociology departments.     

Analysing change in clinical trials using quasi-likelihoods

In clinical trials, investigations focus upon whether a treatment affects a measured outcome. Data often collected include pre- and post-treatment measurements on each patient and an analysis of the change in the outcome is typically performed to determine treatment efficacy. Absolute change and relative change are frequently selected as the outcome. In selecting from these two measures, the analyst makes implicit assumptions regarding the mean and variance-mean relationship of the data. Some have provided ad hoc guidelines for selecting between the two measures. We present a more rigorous means of investigating change using quasi-likelihoods. We show that both absolute change and relative change are special cases of the specified quasi-likelihood model. A cystic fibrosis example is provided.     

THE EXTENDED COASE THEOREM AND LONG RUN EQUILIBRIUM: THE NONEQUIVALENCE OF LIABILITY RULES AND PROPERTY RIGHTS

Many authors have held that in a world with reasonable positive transactions costs, the assignment of liability for pollution damages affects profits, thus long run equilibrium. Therefore, the Coase Theorem fails for such cases. Others have defended the Theorem in such situations .
This paper shows that the disagreement has its roots in a confusion of liability rules and property rights. A simple general equilibrium model is used to show that the Theorem is correct for property rights assignments, but not for liability rules. Liability rules are shown to be, in effect, incomplete property rights, which leads to inefficiency .     

Labor Market Search and Optimal Retirement Policy

A popular and long‐standing view is that social security is a means for young, unemployed people to “purchase” jobs from older workers. Can social security, by encouraging retirement and hence creating job vacancies for the young, improve the allocation of workers to jobs? Maybe, according to a standard model of labor market search, but public retirement programs currently pay the elderly substantially more than their jobs are worth. An important effect is that retirement reduces the value of other vacant jobs. Our results imply that recent reforms aimed at reducing retirement incentives are likely to improve labor market efficiency.