A Bayesian approach for parameter estimation in multi-stage models

Multi-stage time evolving models are common statistical models for biological systems, especially insect populations. In stage-duration distribution models, parameter estimation for the models use the Laplace transform method. This method involves assumptions such as known constant shapes, known constant rates or the same overall hazard rate for all stages. These assumptions are strong and restrictive. The main aim of this paper is to weaken these assumptions by using a Bayesian approach. In particular, a Metropolis-Hastings algorithm based on deterministic transformations is used to estimate parameters. We will use two models, one which has no hazard rates, and the other has stage-wise constant hazard rates. These methods are validated in simulation studies followed by a case study of cattle parasites. The results show that the proposed methods are able to estimate the parameters comparably well, as opposed to using the Laplace transform methods.     

On the asymptotic non‐equivalence of efficient‐GMM and MEL estimators in models with missing data

The generalized method of moments (GMM) and empirical likelihood (EL) are popular methods for combining sample and auxiliary information. These methods are used in very diverse fields of research, where competing theories often suggest variables satisfying different moment conditions. Results in the literature have shown that the efficient‐GMM (GMM_E) and maximum empirical likelihood (MEL) estimators have the same asymptotic distribution to order n^?1/2 and that both estimators are asymptotically semiparametric efficient. In this paper, we demonstrate that when data are missing at random from the sample, the utilization of some well‐known missing‐data handling approaches proposed in the literature can yield GMM_E and MEL estimators with nonidentical properties; in particular, it is shown that the GMM_E estimator is semiparametric efficient under all the missing‐data handling approaches considered but that the MEL estimator is not always efficient. A thorough examination of the reason for the nonequivalence of the two estimators is presented. A particularly strong feature of our analysis is that we do not assume smoothness in the underlying moment conditions. Our results are thus relevant to situations involving nonsmooth estimating functions, including quantile and rank regressions, robust estimation, the estimation of receiver operating characteristic (ROC) curves, and so on.     

Spousal Interdependence in Turnover Decisions: The Case of Israel's Medical Sector Employees

Gender-related labor behavior traditionally has been sensitive to and symptomatic of changes in the labor force and the social structure. Two developments in family life call into question the traditional gender model of work behavior, which posits the family versus job dichotomy: (a) the greater share of economic responsibilities assumed by female spouses, and (b) the greater male involvement in family life within married couple families. A multivariate model that encompasses demographics, work conditions, and family constraints was regressed on the actual turnover behavior of male and female spouses. The analysis reveals that male and female respondents differ in the importance they assign to employment conditions and work attitudes, but they do not differ in the importance they assign to the other spouse's employment and family responsibilities when a turnover decision is considered. These findings support the notion of spousal interdependence in turnover decisions. This interdependence nevertheless is asymmetrical, since the turnover antecedents are caused by the impact of different predictors for men and women.     

Some Properties of the Liang-Zeger Method Applied to Clustered Binary Regression

The Generalized Estimating Equation (GEE) method popularized by Liang and Zeger provides a very general method for fitting regression models to observations that occur in clusters. Features of the method are the specification of a 'working correlation' (a guess at the true correlation structure of the data) which is used to improve efficiency in estimating the regression coefficients, and the 'information sandwich' which provides a way of consistently estimating the standard errors of the estimated regression coefficients even if (as we might expect) the working correlation is wrong. This paper develops asymptotic expressions for the bias and efficiency both of the regression coefficient estimates and of the sandwich estimate, and uses them to study the behaviour of the estimates.
It looks at the effect of the choice of the working correlation on the estimate and also examines the effect of different cluster sizes and different degrees of correlation between the covariates. The performance of these methods is found to be excellent, particularly when the degree of correlation in the responses and covariates is small to moderate.     

The Dearing Report and Students with Disabilities and Learning Difficulties

The movement to promote improved levels of participation from groups under-represented in higher education which occurred between 1980 and 1990 neglected disabled people. The position has been addressed by the national higher education funding councils since 1992 and progress has been made. Therefore, it was surprising to find that, whilst certain social groups were highlighted, nothing was said about disabled people in the terms of reference of Sir Ron Dearing's National Committee of Inquiry. This paper describes attempts made to inform and influence the Committee. Next, it considers the Report itself. First, the recommendations for future policy which are directed specifically towards disabled people are discussed; secondly, the potential implications for disabled people of the general recommendations are explored; and thirdly, the supplementary report on students with disabilities is reviewed. The conclusion provides a brief overview of developments since the Report's publication.     

Reading Rites: Teaching Textwork in Graduate Education

The ability to comprehend, discuss, and use disciplinary texts is central to graduate education. Although techniques for teaching writing have been well-discussed, and even incorporated into graduate curricula, the same is not true for techniques of scholarly reading, a crucial skill that is largely untaught and which students must learn independently or through shared culture. We argue that more explicit training in reading has potential benefits for graduate student education. Drawing on thirty-six in-depth interviews with students in the social sciences, we focus on the routines of managing academic reading, necessary for accessing information for research. Graduate students develop techniques and schedules that permit them to read rapidly or carefully, to read for different academic purposes, and to make information retrievable through notating. We suggest how graduate programs might incorporate reading education into the curriculum.     

Eating together and eating alone: meal arrangements in British households

Sociology traditionally accounts for eating in terms of the social organization of meals, their provision and consumption. A recurrent public concern is that the meal is being subverted. This paper examines meal arrangements in British households in 2012, drawing on an online survey in the format of a food diary administered to 2784 members of a supermarket consumer panel. It charts the organization of contemporary eating occasions, paying attention to socio‐demographic variation in practice. Especially, it explores companionless meals, putting them in contexts of food provisioning and temporal rhythms. Findings show that eating alone is associated with simpler, quicker meals, and that it takes place most commonly in the morning and midday. Those living alone eat alone more often, but at similar meal times, and they take longer over their lone meals. Comparison with a similar study in 1955–6 suggests some fragmentation or relaxation in collective schedules. The implications are not straightforward, and the causes probably lie more in institutional shifts than personal preferences. Declining levels of commensality are, however, associated with a reduction in household size and, especially in households with children, difficulties of coordinating family members’ schedules.     

Online set multicover algorithms for dynamic D2D communications

Motivated by the dynamic resource allocation problem for device-to-device (D2D) communications, we study the online set multicover problem (OSMC). In the online set multicover, the set X of elements to be covered is unknown in advance; furthermore, the coverage requirement of each element \(x \in X\) is initially unknown. Elements of X together with coverage requirements are presented one at a time in an online fashion; and a feasible solution must be maintained at all times. We provide the first deterministic, online algorithms for OSMC with competitive ratios. We consider two versions of OSMC; in the first, each set may be picked only once, while the second version allows each set to be picked multiple times. For both versions, we present the first deterministic, online algorithms, with competitive ratios \(O( \log n \log m )\) and \(O( \log n (\log m + \log k) )\), repectively, where n is the number of elements, m is the number of sets, and k is the maximum coverage requirement. By simulation, we show the efficacy of these algorithms for resource allocation in the D2D setting by analyzing network throughput and other metrics, obtaining a large improvement in running time over offline methods.