海岛野外生存拓展项目产业化初探——以浙江海洋学院海岛野外生存实验基地为例

海岛野外生存拓展项目作为一种新兴运动项目,逐步得到社会各界的关注和认可。随着人们休闲方式日趋团队性、挑战性、亲近自然性,更多的人们参与到海岛野外生存拓展运动中来。本文通过对浙江海洋学院海岛野外生存实验基地的研究,就如何利用该基地促进海岛野外生存拓展项目产业化,使其走向市场,服务社会的可行性进行初步的探究。     

The application of bespoke spending functions in group‐sequential designs and the effect of delayed treatment switching in survival trials

For a group‐sequential trial with two pre‐planned analyses, stopping boundaries can be calculated using a simple SAS? programme on the basis of the asymptotic bivariate normality of the interim and final test statistics. Given the simplicity and transparency of this approach, it is appropriate for researchers to apply their own bespoke spending function as long as the rate of alpha spend is pre‐specified. One such application could be an oncology trial where progression free survival (PFS) is the primary endpoint and overall survival (OS) is also assessed, both at the same time as the analysis of PFS and also later following further patient follow‐up. In many circumstances it is likely, if PFS is significantly extended, that the protocol will be amended to allow patients in the control arm to start receiving the experimental regimen. Such an eventuality is likely to result in the diminution of any effect on OS. It is shown that spending a greater proportion of alpha at the first analysis of OS, using either Pocock or bespoke boundaries, will maintain and in some cases result in greater power given a fixed number of events. Copyright © 2009 John Wiley & Sons, Ltd.     

A Power Analysis of Tests for Paired Lifetime Data

A power analysis is used to compare tests developed for a new lifetime model applicable for certain paired-data experiments. Two pivotal quantities are available for exact parametric testing of the equality of the marginal survival distributions. Here, the power of each test will be calculated to find the more powerful test. The analysis leads to an interesting scenario where the two power curves are quite similar and less powerful test may actually be preferred for pragmatic considerations.     

Modeling the Agreement of Discrete Bivariate Survival Times using Kappa Coefficient

Using local kappa coefficients, we develop a method to assess the agreement between two discrete survival times that are measured on the same subject by different raters or methods. We model the marginal distributions for the two event times and local kappa coefficients in terms of covariates. An estimating equation is used for modeling the marginal distributions and a pseudo-likelihood procedure is used to estimate the parameters in the kappa model. The performance of the estimation procedure is examined through simulations. The proposed method can be extended to multivariate discrete survival distributions.     

Multivariate Parametric Spatiotemporal Models for County Level Breast Cancer Survival Data

In clustered survival settings where the clusters correspond to geographic regions, biostatisticians are increasingly turning to models with spatially distributed random effects. These models begin with spatially oriented frailty terms, but may also include further region-level terms in the parametrization of the baseline hazards or various covariate effects (as in a spatially-varying coefficients model). In this paper, we propose a multivariate conditionally autoregressive (MCAR) model as a mixing distribution for these random effects, as a way of capturing correlation across both the regions and the elements of the random effect vector for any particular region. We then extend this model to permit analysis of temporal cohort effects, where we use the term temporal cohort to mean a group of subjects all of whom were diagnosed with the disease of interest (and thus, entered the study) during the same time period (say, calendar year). We show how our spatiotemporal model may be efficiently fit in a hierarchical Bayesian framework implemented using Markov chain Monte Carlo (MCMC) computational techniques. We illustrate our approach in the context of county-level breast cancer data from 22 annual cohorts of women living in the state of Iowa, as recorded by the Surveillance, Epidemiology, and End Results (SEER) database. Hierarchical model comparison using the Deviance Information Criterion (DIC), as well as maps of the fitted county-level effects, reveal the benefit of our approach.     

中国石油存续企业改革的思路及其发展

石油存续企业改革的思路是:产权明晰;产权多元化是存续企业改革的方向;产权的可交易性;让企业来发挥作用。“退”是石油存续企业发展的前提与关键。     

The Additive Nonparametric and Semiparametric Aalen Model as the Rate Function for a Counting Process

We use the additive risk model of Aalen (Aalen, 1980) as a model for the rate of a counting process. Rather than specifying the intensity, that is the instantaneous probability of an event conditional on the entire history of the relevant covariates and counting processes, we present a model for the rate function, i.e., the instantaneous probability of an event conditional on only a selected set of covariates. When the rate function for the counting process is of Aalen form we show that the usual Aalen estimator can be used and gives almost unbiased estimates. The usual martingale based variance estimator is incorrect and an alternative estimator should be used. We also consider the semi-parametric version of the Aalen model as a rate model (McKeague and Sasieni, 1994) and show that the standard errors that are computed based on an assumption of intensities are incorrect and give a different estimator. Finally, we introduce and implement a test-statistic for the hypothesis of a time-constant effect in both the non-parametric and semi-parametric model. A small simulation study was performed to evaluate the performance of the new estimator of the standard error.     

On assessing independence of Competing Risks when failure times are discrete

The traditional approach to modelling for Competing Risks, via a multivariate distribution of latent failure times, is very natural for many applications but suffers from a well-documented problem of identifiability. However, the demonstrations of this problem in the literature apply to essentially continuous latent failure times where any atoms of probability in their distributions are not too intrusive. It is shown in this paper that for discrete failure times the classic results on the identifiability problem concerning the existence of equivalent independent risks are incomplete.     

Nonparametric density estimation for censored survival data: Regression-spline approach

A method for nonparametric estimation of density based on a randomly censored sample is presented. The density is expressed as a linear combination of cubic M -splines, and the coefficients are determined by pseudo-maximum-likelihood estimation (likelihood is maximized conditionally on data-dependent knots). By using regression splines (small number of knots) it is possible to reduce the estimation problem to a space of low dimension while preserving flexibility, thus striking a compromise between parametric approaches and ordinary nonparametric approaches based on spline smoothing. The number of knots is determined by the minimum AIC. Examples of simulated and real data are presented. Asymptotic theory and the bootstrap indicate that the precision and the accuracy of the estimates are satisfactory.     

求解乡镇政府"非法生存"的困境

乡镇是我国行政管理层次中最低一级的行政建制,它责任重大,但处境窘迫。乡镇政府违法“寻租”、“创收”的“非法生存”现象非常普遍,危害十分严重。究其原因既有政治方面的,也有经济方面的。要从行政体制、财政经济改革和强化依法行政等方面来杜绝其“非法生存”。