A nonparametric estimator of the number of classes based on a stratified random sample

Under stratified random sampling, we develop a k^th-order bootstrap bias-corrected estimator of the number of classes θ which exist in a study region. This research extends Smith and van Belle’s (1984) first-order bootstrap bias-corrected estimator under simple random sampling. Our estimator has applicability for many settings including: estimating the number of animals when there are stratified capture periods, estimating the number of species based on stratified random sampling of subunits (say, quadrats) from the region, and estimating the number of errors/defects in a product based on observations from two or more types of inspectors. When the differences between the strata are large, utilizing stratified random sampling and our estimator often results in superior performance versus the use of simple random sampling and its bootstrap or jackknife [Burnham and Overton (1978)] estimator. The superior performance is often associated with more observed classes, and we provide insights into optimal designation of the strata and optimal allocation of sample sectors to strata.     

Neuropathology in Alzheimer's disease: awaking from a hundred-year-old dream

For one hundred years after Alois Alzheimer's first report of Alzheimer's disease (AD) in 1906, the pathological hallmarks of the disease, senile plaques and neurofibrillary tangles (NFTs), have been attractive targets for researchers. Therefore, not surprisingly, efforts to understand disease mechanisms have concentrated on the cell biology of amyloid-beta (Abeta) deposition as senile plaques or on the phosphorylation and aggregation of tau as NFTs. However, it now appears that this focus on pathology as a central contributor to disease may be misguided. Indeed, neurons associated with Abeta and NFTs in AD brain show a decrease in oxidative damage relative to those in vulnerable but morphologically intact areas of the brain, suggesting that neurodegenerative lesions are compensatory phenomena, and thus manifestations of cellular adaptation. That Abeta and tau accumulations indicate an age-related physiological reaction to chronic stress calls into question the rationale of current therapeutic efforts targeted toward lesion removal. Moreover, if this concept holds true for pathology in other neurodegenerative diseases, we may need to restructure our thinking and undergo a paradigm shift before substantial progress can be made in therapeutic intervention.     

FATHERS TAKING PARENTAL LEAVE AND THEIR INVOLVEMENT WITH CHILDREN

Parental leave has been promoted as a way to enhance employed fathers’ involvement with their children. Leave patterns, factors affecting these patterns and the impact of taking leave on involvement with children were assessed for fathers in 38 couples. Parents, contacted through their employers, completed self-administered questionnaires on their work schedule changes after the arrival of a baby, reactions to these changes, childcare activities and attitudes. The mother's and father's assessments in each couple were averaged to measure 21 different aspects of fathers’ involvement. Fathers who took leave were more likely to share some specific childcare tasks with mothers than fathers who did not take leave but no differences were found for time spent with children or taking responsibility for childcare. Parents’ equalitarian beliefs, income and education had more impact than taking leave on fathers’ overall involvement in childcare.

Se ha promovido La Licencia de Paternidad como una forma para ayudar a los padres que están empleados a involucrarse con sus hijos. Los patrones de estas licencias, los factores que afectan estos patrones, y el impacto que tiene esta licencia en las relaciones con los niños fueron evaluadas por los padres en 38 parejas. Los padres, contactados por sus empleadores, completaron cuestionarios sobre los cambios en sus horarios de trabajo después de la llegada del bebé, las reacciones a esos cambios, actividades para el cuidado del niño, y sus actitudes. Se hizo un promedio midiendo los 21 diferentes aspectos del involucro de los padres presentado en las evaluaciones hechas por la madre y el padre en cada pareja. Los padres que tomaron licencia de paternidad, generalmente compartieron con la madre algunos aspectos específicos para el cuidado del niño a diferencia de los padres que no tomaron la licencia, pero no se encontraron diferencias sobre el tiempo empleado con los niños o en las responsabilidades del cuidado de los mismos. En general, las creencias sobre la igualdad, la situación económica y la educación de los padres, tuvo más impacto que el involucrarse totalmente en el cuidado de los niños de los padres con licencia de paternidad.     

A threshold autoregressive model for wholesale electricity prices

Summary.  We introduce a discrete time model for electricity prices which accounts for both transitory spikes and temperature effects. The model allows for different rates of mean reversion: one for weather events, one around price jumps and another for the remainder of the process. We estimate the model by using a Markov chain Monte Carlo approach with 3 years of daily data from Allegheny County, Pennsylvania. We show that our model outperforms existing stochastic jump diffusion models for this data set. Results also demonstrate the importance of model parameters corresponding to both the temperature effect and the multilevel mean reversion rate.     

THE McMASTER FAMILY ASSESSMENT DEVICE*

This paper describes the McMaster Family Assessment Device (FAD), a newly developed questionnaire designed to evaluate families according to the McMaster Model of Family Functioning. The FAD is made up of seven scales which measure Problem Solving, Communication, Roles, Affective Responsiveness, Affective Involvement, Behavior Control and General Functioning. The paper describes the procedures used to develop the FAD and presents scale means and scale reliabilities from a sample of 503 individuals.     

Unbinding Time: Alternate Work Schedules and Work-Life Balance

We examine the possibility that alternate work schedules affect perceived work-life imbalance—the time bind. The results show that alternate schedules per se do not unbind time. However, perceived control of work schedules increases work-life balance net of family and work characteristics. The most consistent family characteristic predicting imbalance is being a parent. The most consistent work characteristic predicting imbalance is hours worked. Once we control for hours worked, women and part-timers are shown to perceive more imbalance. Younger and better educated persons also perceive more work-life imbalance. However, they also report higher levels of schedule control and since schedule control improves work-life balance, it may be more important for unbinding time than schedule alternatives.     

Social Cocoons: Encapsulation and Identity Transformation Organizations*

The transformation of personal identities is an implicit or explicit goal of many organizations, including “new” religious movements, self-help groups, “deprogramming” enterprises, rehabilitation programs, and others. This essay describes and accounts for one important structural feature of identity transformation organizations (ITOs): encapsulation. Three types of encapsulation are described–physical, social, and ideological–and reasons why different ITOs emphasize certain types of encapsulation rather than others are suggested. Finally, we discuss how the need for encapsulation may conflict with other organizational imperatives of ITOs and we discuss the implications of this organizational dilemma for the successful functioning of ITOs.     

Letter to the Editor: A reply to Klein and Stern

Klein and Stern (hereafter KS-2007) have several problems withour article ("Is the Academy a Liberal Hegemony"), with themost general being their contention that we "misrepresent" theirwork. Most of this hinges on their claim that, while they studiedthe proportion of faculty who register or vote Democratic orRepublican (their D:R ratio), we treated this as equivalentto a measure of liberalism versus conservatism. KS-2007 go onto say that we "impute ideological content" to their resultswhile they themselves claim the intellectual high road as havingbeen very careful not to conflate voting or party registrationwith     

Caregivers as Interventionists and Trainers: Teaching Mands to Children with Developmental Disabilities

The Analysis of Verbal Behavior - We evaluated the use of behavioral skills training (BST) to train caregivers to conduct procedures commonly associated with mand training. We trained two...