A Three‐step Method for Choosing the Number of Bootstrap Repetitions

This paper considers the problem of choosing the number of bootstrap repetitions B for bootstrap standard errors, confidence intervals, confidence regions, hypothesis tests, p‐values, and bias correction. For each of these problems, the paper provides a three‐step method for choosing B to achieve a desired level of accuracy. Accuracy is measured by the percentage deviation of the bootstrap standard error estimate, confidence interval length, test's critical value, test's p‐value, or bias‐corrected estimate based on B bootstrap simulations from the corresponding ideal bootstrap quantities for which B=∞. The results apply quite generally to parametric, semiparametric, and nonparametric models with independent and dependent data. The results apply to the standard nonparametric iid bootstrap, moving block bootstraps for time series data, parametric and semiparametric bootstraps, and bootstraps for regression models based on bootstrapping residuals. Monte Carlo simulations show that the proposed methods work very well.     

the Block–Block Bootstrap: Improved Asymptotic Refinements

The asymptotic refinements attributable to the block bootstrap for time series are not as large as those of the nonparametric iid bootstrap or the parametric bootstrap. One reason is that the independence between the blocks in the block bootstrap sample does not mimic the dependence structure of the original sample. This is the join‐point problem. In this paper, we propose a method of solving this problem. The idea is not to alter the block bootstrap. Instead, we alter the original sample statistics to which the block bootstrap is applied. We introduce block statistics that possess join‐point features that are similar to those of the block bootstrap versions of these statistics. We refer to the application of the block bootstrap to block statistics as the block–block bootstrap. The asymptotic refinements of the block–block bootstrap are shown to be greater than those obtained with the block bootstrap and close to those obtained with the nonparametric iid bootstrap and parametric bootstrap.     

Adaptive Local Polynomial Whittle Estimation of Long‐range Dependence

The local Whittle (or Gaussian semiparametric) estimator of long range dependence, proposed by Künsch (1987) and analyzed by Robinson (1995a), has a relatively slow rate of convergence and a finite sample bias that can be large. In this paper, we generalize the local Whittle estimator to circumvent these problems. Instead of approximating the short‐run component of the spectrum, ϕ(λ) , by a constant in a shrinking neighborhood of frequency zero, we approximate its logarithm by a polynomial. This leads to a “local polynomial Whittle” (LPW) estimator. We specify a data‐dependent adaptive procedure that adjusts the degree of the polynomial to the smoothness of ϕ(λ) at zero and selects the bandwidth. The resulting “adaptive LPW” estimator is shown to achieve the optimal rate of convergence, which depends on the smoothness of ϕ(λ) at zero, up to a logarithmic factor.     

Hunger,nutrition, and precipitation: evidence from Ghana and Bangladesh

Population and Environment - Changing precipitation patterns caused by climate change are expected to have major impacts on food security and nutrition in agrarian areas in developing countries....     

Exposing School Employee Sexual Abuse and Misconduct: Shedding Light on a Sensitive Issue

ABSTRACT

While the media continue to report incidents of school employee sexual misconduct, few empirical studies focus on this issue. To address this gap in the literature, expand knowledge and awareness around the problem, and inform future research and programs, this research intends to document and analyze the characteristics of school employee sexual misconduct cases reported in the media. The authors conducted a landscape analysis of 361 published school employee sexual misconduct cases in the United States from 2014, documenting factors such as offender and victim characteristics, type of incident, technology use, location of offense, and resulting disciplinary actions by schools and law enforcement. These analyses showed that offenders were most often male and general education teachers, with approximately a quarter identified as athletic coaches. Offenders’ average age was 36 years, while the average age of victims was 15. More than half of incidents took place at school or school-related events. Results also showed that school employee sexual misconduct incidents most often involved physical contact; however, technology (i.e., cell phones, computers, cameras/video recorders, and storage devices) played an important role in three out of four cases. Finally, analyses of the criminal and school-related consequences showed that over half of offenders were placed on administrative leave or resigned immediately following their arrest and almost all were convicted of their crimes. Additional findings concerning this topic are also reported in this article.     

Client Experiences of Trauma-Informed Care in Social Service Agencies

This paper describes a qualitative study of individual client interviews (n?=?26) from four social service agencies to understand how clients experience trauma-informed care services and implementation challenges. We used the Fallot and Harris framework to explore client experiences of the five core concepts of trauma-informed care (safety, trustworthiness, choice, collaboration, and empowerment) using semi-structured interview questions with each client. The four agencies consisted of: refugees (n?=?4), substance abuse (n?=?8), older adults (n?=?12), and maternal/child health (n?=?2), and the agencies varied in size, service goals, and clientele. The results of the study suggest that clients’ experience of these concepts was shaped by the actions of other clients, and these experiences were either mitigated or hindered by actions of the agency employees. Agency policies either supported or enhanced their experiences as well. The results also suggest that it was challenging for agencies to provide for all of the trauma-informed care (TIC) concepts at the same time. We discuss the implications of these findings for social service delivery in a range of agency types. Future research should examine the effects of trauma-informed policies on client experiences of each TIC domain.     

Unexpecting age

This essay argues that how we view our own old age is highly influenced by socially pervasive, though never explicit, expectations regarding old age as a generic category. I idenfiy four key expectations - the right to an old age; the idea that being old means being endowed with certain (positive or negative) characteristics; the fragmented relationship between the phases of life; and the assumption of the a-social nature of the aging process - and explore the sometimes contradictory ways in which these impact upon our own journeys through the life course.     

Sequential case series analysis for pharmacovigilance

Summary.  The self-controlled case series method is used to evaluate drug safety, particularly the safety of paediatric vaccines with respect to rare adverse reactions. We propose a group sequential version of the method for prospective surveillance of drug safety. We focus on the surveillance of new vaccines. We develop methods that are based on the sequential probability ratio test applied at predetermined surveillance intervals, using both simple and composite alternative hypotheses. We investigate the properties of the methods analytically in a simple setting and by simulations in more realistic scenarios. The methods are applied to data on influenza vaccine and Bell's palsy, and to data on measles, mumps and rubella vaccine and bleeding disorders.     

Perceptions of Academic Achievement and Educational Opportunities Among Black and African American Youth

Research focusing on disparities in academic achievement among Black, African American, and other youth has largely examined differences in quantitative risk and protective factors associated with levels of achievement. Few interpretive studies of academic achievement by race or ethnicity have considered how the context of young people’s lives impact their perceptions of academic performance. Furthermore, the lived experiences of Black and African American youth have rarely been considered. This study examined perceptions of academic achievement among a sample of Black and African American elementary and middle school students living in four public housing neighborhoods in a Western US city. Twenty-five Black and African American youth participated in the study. Fourteen youth were in grades 4 and 5, and 11 youth were in grades 6, 7, or 8. Sixty-four percent of participants (n?=?16) were male and 36% (n?=?9) were female. Four themes emerged regarding participants’ perceptions of academic achievement: (1) (in)equity and the internalization of messages; (2) teachers as gatekeepers; (3) family and community factors promoting and inhibiting academic success; and (4) cultural considerations—language, stereotypes, and difference. Implications for improving academic outcomes and reducing the achievement gap among Black, African American, and other students are noted.     

Stakeholder perspectives on integrated services for people who experience chronic homelessness

This article concerns a SAMHSA-funded service intervention, Pathways to Independence, that combined the use of SAMHSA’s SSI/SSDI Outreach, Access, and Recovery approach to facilitating disability entitlement claims with financial management classes, mental health assessment and referral, and access to employment and housing for people experiencing chronic homelessness. The purpose of this study was to explore perceptions of this form of service delivery and the benefits and challenges of the program model from the perspective of those who experienced it. Focus groups were conducted with a total of 17 program stakeholders, including program participants, program staff, collaborating case management staff of the parent agency, and a landlord and an employer, with questions to each regarding the program and its impact. Focus groups were analyzed through independent coding followed by discussion to reach consensus on key themes. Five themes were identified across the groups: (a) the importance of relationships, (b) staff specialization and provision of individualized services, (c) an orientation to outcomes, (d) comprehensiveness of services and facilitation of connections to community resources, and (e) systems challenges. The Pathways to Independence program provides a working model for integrated employment, entitlement assessment and application, housing, and behavioral health treatment for persons experiencing chronic homelessness.