A new approach to statistical efficiency of weighted least squares fitting algorithms for reparameterization of nonlinear regression models

We study nonlinear least-squares problem that can be transformed to linear problem by change of variables. We derive a general formula for the statistically optimal weights and prove that the resulting linear regression gives an optimal estimate (which satisfies an analogue of the Rao-Cramer lower bound) in the limit of small noise.     

Student-t censored regression model: properties and inference

In statistical analysis, particularly in econometrics, it is usual to consider regression models where the dependent variable is censored (limited). In particular, a censoring scheme to the left of zero is considered here. In this article, an extension of the classical normal censored model is developed by considering independent disturbances with identical Student-t distribution. In the context of maximum likelihood estimation, an expression for the expected information matrix is provided, and an efficient EM-type algorithm for the estimation of the model parameters is developed. In order to know what type of variables affect the income of housewives, the results and methods are applied to a real data set. A brief review on the normal censored regression model or Tobit model is also presented.     

The ℓ1 oblique procrustes problem

In this paper, we reconsider the well-known oblique Procrustes problem where the usual least-squares objective function is replaced by a more robust discrepancy measure, based on the ₁ norm or smooth approximations of it.We propose two approaches to the solution of this problem. One approach is based on convex analysis and uses the structure of the problem to permit a solution to the ₁ norm problem. An alternative approach is to smooth the problem by working with smooth approximations to the ₁ norm, and this leads to a solution process based on the solution of ordinary differential equations on manifolds. The general weighted Procrustes problem (both orthogonal and oblique) can also be solved by the latter approach. Numerical examples to illustrate the algorithms which have been developed are reported and analyzed.     

Bayesian prediction for progressively censored data from the Burr model

Received: August 14, 2000; revised version: April 23, 2001     

Random effects and shrinkage estimation in capture-recapture models

We discuss the analysis of random effects in capture-recapture models, and outline Bayesian and frequentists approaches to their analysis. Under a normal model, random effects estimators derived from Bayesian or frequentist considerations have a common form as shrinkage estimators. We discuss some of the difficulties of analysing random effects using traditional methods, and argue that a Bayesian formulation provides a rigorous framework for dealing with these difficulties. In capture-recapture models, random effects may provide a parsimonious compromise between constant and completely time-dependent models for the parameters (e.g. survival probability). We consider application of random effects to band-recovery models, although the principles apply to more general situations, such as Cormack-Jolly-Seber models. We illustrate these ideas using a commonly analysed band recovery data set.     

简论文学作品在高校思想政治理论课教学中的运用

文学作品运用于高校思想政治理论课教学中,可以采用直接引用原文、间接叙述、直接引用和间接叙述相结合的方式,以及引导学生回忆记忆中的文学作品等方式。为了达到良好的教学效果,文学作品可以与朗诵、音乐、影视以及图片等形式相结合展现出来。在选择文学作品作为思想政治理论课教学素材时,应尽量选择学生较为熟悉的和易懂的文学作品,文学作品的内容应与教学内容相当,不宜过多,以免喧宾夺主。     

Choice and circumstance: Qualitative insights into contemporary childlessness in Australia

Using data from in-depth interviews with 115 women, men and couples in eastern Australia for whom family formation was a recent, current or imminent future issue, this article explores contemporary childlessness among those physically able to have children. It differentiates between those childless by choice and by circumstance, and among other themes highlights (i) the role preservation of lifestyle appears to play as a motive for deliberate childlessness following development of a life course through early adulthood that both generates lifestyle aspirations and often places parenthood on the backburner until after age 30, and (ii) the roles difficulty forming suitable relationships, women’s desire for meaningful careers, and male involvement in family formation decisions play in bringing about childlessness by circumstance.     

Sexual trafficking in women: international political economy and the politics of sex

A recent manifestation of the North/South, East/West political-economic divide is the international sex trade in women, of which trafficking in women for purposes of sexual employment is a large subset. Trafficking in humans in general, and women in particular, has taken center stage in many nation-states as an issue of a threat to national security and societal cohesion. This article explores some of the basic facts about trafficking and spotlights it as a truly global phenomenon, with its contemporary origins in the international capitalist market system. Furthermore, it argues that the international political economy of sex not only includes the supply side--the women of the third world, the poor states, or exotic Asian women--but it cannot maintain itself without the demand from the organizers of the trade--the men from industrialized and developing countries. The patriarchal world system hungers for and sustains the international subculture of docile women from underdeveloped nations.     

An empirical investigation of human dyadic systems in the time and frequency domains

This paper presents time and frequency domain analyses of psychotherapy data drawn from a unique dyadic system--the patient/therapist (P/T) system. The data are constituted by a time series defined by which member of the P/T system held the speaker role at each second of ten recorded psychotherapy consultations. The series reflects a specific property of communication within the dyad. Each series significantly followed a first order autoregressive model. That is, each was highly sensitive to the prior state of the system, or equivalently, the system showed feedforward of its prior state. These models became more significant after intervention analysis further clarified the underlying autoregressive structure. The histograms of the frequency of the length of each utterance indicated an underlying Poisson model for the emergence of speech. The parameters of the Poisson and autoregressive models were used to determine blindly which of four pairs of interviews involved the same therapist with two different patients. The method correctly identified three of the therapist four pairs but failed to identify different interviews with the same patient, a significantly negative result. These results suggest that certain time domain measures are therapist-dominated, so that the therapist drives change in these areas within the P/T system more strongly than the patient. In the frequency domain, the coherency between each of the 45 pairs of speaker series was used in an attempt to identify which time series corresponded systematically to the same therapists or patients. This proved futile because no two pairs of series--no P/T system--showed significant non-zero coherency. This result suggests that the harmonics of the switching of the speaker role are not determined by the therapist or patient alone but by the P/T system as an entity. We conclude that human dyadic systems may show predominant influence of one member or jointly determined patterns that are highly distinctive.     

A ratio-to-control Williams-type test for trend

Under certain conditions, many multiple contrast tests based on the difference of treatment means can also be conveniently expressed in terms of ratios. In this paper, a Williams test for trend is defined as ratios-to-control for ease of interpretation and to obtain directly comparable confidence intervals. Simultaneous confidence intervals for percentages are particularly helpful for interpretations in the case of multiple endpoints. Methods for constructing simultaneous confidence intervals are discussed under both homogeneous and heterogeneous error variances. This approach is available in the R extension package mratios. The proposed method is used to test for trend in an immunotoxicity study with several endpoints as an example.