Accounting for Uncertainty in Heteroscedasticity in Nonlinear Regression

Toxicologists and pharmacologists often describe toxicity of a chemical using parameters of a nonlinear regression model. Thus estimation of parameters of a nonlinear regression model is an important problem. The estimates of the parameters and their uncertainty estimates depend upon the underlying error variance structure in the model. Typically, a priori the researcher would not know if the error variances are homoscedastic (i.e., constant across dose) or if they are heteroscedastic (i.e., the variance is a function of dose). Motivated by this concern, in this paper we introduce an estimation procedure based on preliminary test which selects an appropriate estimation procedure accounting for the underlying error variance structure. Since outliers and influential observations are common in toxicological data, the proposed methodology uses M-estimators. The asymptotic properties of the preliminary test estimator are investigated; in particular its asymptotic covariance matrix is derived. The performance of the proposed estimator is compared with several standard estimators using simulation studies. The proposed methodology is also illustrated using a data set obtained from the National Toxicology Program.     

A latent variable model for analyzing mixed longitudinal (k,l)-inflated count and ordinal responses

A random effects model for analyzing mixed longitudinal count and ordinal data is presented where the count response is inflated in two points (k and l) and an (k,l)-Inflated Power series distribution is used as its distribution. A full likelihood-based approach is used to obtain maximum likelihood estimates of parameters of the model. For data with non-ignorable missing values models with probit model for missing mechanism are used.The dependence between longitudinal sequences of responses and inflation parameters are investigated using a random effects approach. Also, to investigate the correlation between mixed ordinal and count responses of each individuals at each time, a shared random effect is used. In order to assess the performance of the model, a simulation study is performed for a case that the count response has (k,l)-Inflated Binomial distribution. Performance comparisons of count-ordinal random effect model, Zero-Inflated ordinal random effects model and (k,l)-Inflated ordinal random effects model are also given. The model is applied to a real social data set from the first two waves of the national longitudinal study of adolescent to adult health (Add Health study). In this data set, the joint responses are the number of days in a month that each individual smoked as the count response and the general health condition of each individual as the ordinal response. For the count response there is incidence of excess values of 0 and 30.     

Combinations of absorptive capacity metaroutines: The role of organizational disruptions and time constraints

This paper explores absorptive capacity metaroutines in a financial organization that experienced a large-scale misappropriation episode. We selected an instrumental case and collected individual semi-structured interviews, on-site nonparticipant observations, and documents to better understand the combination of absorptive capacity in organizational contexts. Findings revealed that the magnitude of organizational disruptions and time constraints influenced absorptive capacity metaroutines. The magnitude of organizational disruptions related to the intensity of required change for innovation adoption and the persistence of outcomes, while time constraints influenced the degree of involvement and cohesiveness of organizational members. In addition, findings showed that the combination of absorptive capacity metaroutines experienced asymmetries and had incremental and cumulative features. This work extends current theorizations of absorptive capacity conceptualized from a micro-foundation perspective as a collection of external and internal metaroutines and provides a means to start understanding potential factors that influence the combination of absorptive capacity metaroutines. Implications for theory and practice are discussed, and suggestions for future research are offered.     

文化遗产数字化与互动性推广模式——基于新媒介载体的文化产业开发

文化遗产的数字化不仅可以有效保护与传承文化,还可以与新媒介结合进行互动式推广。利用数字技术、网络技术、移动通信技术等新媒介推广文化的模式有:富媒体虚拟场景展示、IGA软性推广、虚拟真实互动等。通过这些方式可实现新媒介与文化遗产推广推介的结合、虚拟场景与真实景观的结合、线上互动与线下互动的结合。通过互动性推广,辐射大众、涵盖小众,并影响多目标人群的参与与关注。     

Math-oriented fields of study and the race gap in graduation likelihoods at elite colleges

This study examines the relationship between chosen field of study and the race gap in college completion among students at elite colleges. Fields of study are characterized by varying institutional arrangements, which impact the academic performance of students in higher education. If the effect of fields on graduation likelihoods is unequal across racial groups, then this may account for part of the overall race gap in college completion. Results from a large sample of students attending elite colleges confirm that fields of study influence the graduation likelihoods of all students, above and beyond factors such as students’ academic and social backgrounds. This effect, however, is asymmetrical: relative to white students, the negative effect of the institutional arrangements of math-oriented fields on graduation likelihood is greater for black students. Therefore, the race gap is larger within math-oriented fields than in other fields, which contributes to the overall race gap in graduation likelihoods at these selective colleges. These results indicate that a nontrivial share of the race gap in college completion is generated after matriculation, by the environments that students encounter in college. Consequently, policy interventions that target field of study environments can substantially mitigate racial disparities in college graduation rates.     

跨文化的解码与建构--论美国汉学家史景迁的孔子研究

美国著名汉学家史景迁(Jonathan D. Spence)从文化认知、文化比较的研究视域出发，对孔子进行了跨文化解读与传播。在史景迁“去偶像化”的观照方式下，孔子被解码、建构为具备鲜明个性特质的人文主义者及令人尊重的教育者形象。同时，史景迁致力于厘清西方一般认知中对孔子及其思想的诸多误读，并努力唤起西方受众对孔子当代意义的认同。     

Emotions in organization–public relationships: Proposing a new determinant

Emotions have been left largely out of debate over the indicators that make up organization–public relationship (OPR) frameworks. This exploratory study analyses the importance of emotions in OPR. Results show that emotions are highly influential in this relationship. On these grounds, the paper suggests expanding existing conceptual analyses of OPR to include emotions.     

Generalizing the standardized hazard ratio to multivariate proportional hazards regression,with an application to clinical~genomic studies

The standardized hazard ratio for univariate proportional hazards regression is generalized as a scalar to multivariate proportional hazards regression. Estimators of the standardized log hazard ratio are developed, with corrections for bias and for regression to the mean in high-dimensional analyses. Tests of point and interval null hypotheses and confidence intervals are constructed. Cohort sampling study designs, commonly used in prospective–retrospective clinical genomic studies, are accommodated.