A Kernel Smooth Approach for Joint Modeling of Accelerated Failure Time and Longitudinal Data

Joint likelihood approaches have been widely used to handle survival data with time-dependent covariates. In construction of the joint likelihood function for the accelerated failure time (AFT) model, the unspecified baseline hazard function is assumed to be a piecewise constant function in the literature. However, there are usually no close form formulas for the regression parameters, which require numerical methods in the EM iterations. The nonsmooth step function assumption leads to very spiky likelihood function which is very hard to find the globe maximum. Besides, due to nonsmoothness of the likelihood function, direct search methods are conducted for the maximization which are very inefficient and time consuming. To overcome the two disadvantages, we propose a kernel smooth pseudo-likelihood function to replace the nonsmooth step function assumption. The performance of the proposed method is evaluated by simulation studies. A case study of reproductive egg-laying data is provided to demonstrate the usefulness of the new approach.     

破产瞬间及前后余额的联合密度函数

本文对古典风险模型给出了破产时间扣破产前后余额三者的联合密度函数表达式.并且由此直接证明了推广的Dickson公式.     

结果加重犯构成新论

晚近以降,结果加重犯适当性问题饱受争议,国内外众多学者以“责任主义”为基础,提倡对其加以废止或修正。但是,当前问题的核心在于我们没有厘清结果加重犯的结构构造,陷入了“复合形态论”的误区。与此相对,在犯罪类型上结果加重犯应当是危险犯的实害形态。据此,结果加重犯的结构构造具备以下特征：一方面,行为人实施的基本犯罪行为在客观上具有产生加重结果的高度风险性;另一方面,行为人主观方面对于加重结果存在危险故意。     

Endogenous Adaptation: The Effects of Technology Position and Planning Mode on IT‐Enabled Change*

The redesign of information technology (IT)‐enabled work processes often necessitates fundamental design changes to the intended work process, the IT platform hosting the work process, or both. Research suggests that such design changes often can be traced to earlier decisions involving endogenous adaptation or internal organizational change. Two such decisions are a firm's technology position and planning mode. This study examines the relationship between technology position and planning mode in predicting the magnitude of design change in process redesign projects. The conceptual frame applied in examining these relationships involves a synthesis of Miles and Snow's adaptive cycle with elements central to concurrent engineering. Our results indicate that the magnitude of design change is related to differences in technology position and planning mode. To effectively implement organizational change, firms must leverage their IT platform by carefully timing IT investments in accordance with their adopted technology position. Directing the trajectory of a firm's IT platform and deploying it so as to complement the firm's technology position reduces design uncertainty, promoting reengineering success.     

Embracing complexity: Learning from minority, 50-50, and majority joint venture experience

Learning from joint venture (JV) experience is commonly viewed as a way to improve JV performance. However, many JVs are complex and difficult to learn from. How can firms embrace this complexity to realize the learning potential of their JV experience? To answer this question, we consider how minority, 50-50, and majority JVs differ in terms of complexity stemming from the interdependencies between the JV partners and between the JV and its parent organizations. We theorize that the relatively limited complexity of minority JV experience facilitates learning from more complex experience with majority and 50-50 JVs. However, the same facilitating effect is not expected between two forms of complex experience. We test these predictions on a comprehensive set of equity JVs formed by Dutch listed companies between 1966 and 2005, using JV survival and abnormal stock market returns as complementary JV performance measures.     

A note on tests for interaction in quantal response data

There are few distribution-free methods for detecting interaction in fixed-dose trials involving quantal response data, despite the fact that such trials are common. We present three new tests to address this issue, including a simple bootstrap procedure. We examine the power of the likelihood ratio test and our new bootstrap test statistic using an innovative linear extrapolation power-estimation technique described in Boos, D. D. and Zhang, J. (2000) in Monte Carlo evaluation of resampling-based hypothesis tests. Journal of the American Statistical Association, 95, 486–492.     

Joint models for a GLM-type longitudinal response and a time-to-event with smooth random effects

ABSTRACT

Longitudinal studies often entail non-Gaussian primary responses. When dropout occurs, potential non-ignorability of the missingness process may occur, and a joint model for the primary response and a time-to-event may represent an appealing tool to account for dependence between the two processes. As an extension to the GLMJM, recently proposed, and based on Gaussian latent effects, we assume that the random effects follow a smooth, P-spline based density. To estimate model parameters, we adopt a two-step conditional Newton–Raphson algorithm. Since the maximization of the penalized log-likelihood requires numerical integration over the random effect, which is often cumbersome, we opt for a pseudo-adaptive Gaussian quadrature rule to approximate the model likelihood. We discuss the proposed model by analyzing an original dataset on dilated cardiomyopathies and through a simulation study.     

A comparison of using weighted distribution and joint modeling for analyzing non-ignorable missing responses

In this study, we reconsider weighted distribution from the perspective of missing mechanism since weighted distribution instead of being the distribution of the whole population of interest is only the distribution of respondents (sub-population). After defining some weighted distributions by different mechanisms for indicator of response, we show, by some simulation studies, that using weighted distributions may lead to biased estimates of parameters under the non-ignorable missing mechanism. On the other hand, joint modeling of the response and selection mechanism could result in more efficient and valid estimates of parameters. The lower root of mean squared errors of estimates from the joint modeling approach than those of the weighted distribution is a warranty to the statement that the joint modeling method is more efficient than weighted distribution; this is proved by diverse simulation studies along the article. However, these two methods of the weighted approach and joint modeling give similar results if the selection mechanism is at random. Finally, the methods are applied and compared in the analysis of one well-used real dataset.     

Measuring the Precision of Statistical Cost Allocations

This article examines the use of regression analysis for allocating indirect costs. When multiple regression is used to estimate the weights of several allocation factors, conventional standard errors and correlation coefficients can be misleading with respect to the statistical precision of the cost allocations. This article develops alternative allocation approaches and measures of precision that use linear prediction theory and Bayesian inference. The proposed methods are illustrated using a university indirect cost study.     

哲学与艺术的共同抵抗——阿多诺对于现代美学的构想及意义

阿多诺美学的出发点在现代艺术,落脚点在拯救现实.他认为,只有把哲学和艺术二者有机结合,才足以让传统美学重新焕发活力,促进艺术的发展,进而挽救处于颓势的人类文明.阿多诺注意挖掘传统美学的潜力、从现代艺术现实出发构建现代美学理论、注重美学理论的开放性,对我国当代美学理论的构建具有借鉴意义.