Acceleration of the Multiple-Try Metropolis algorithm using antithetic and stratified sampling

The Multiple-Try Metropolis is a recent extension of the Metropolis algorithm in which the next state of the chain is selected among a set of proposals. We propose a modification of the Multiple-Try Metropolis algorithm which allows for the use of correlated proposals, particularly antithetic and stratified proposals. The method is particularly useful for random walk Metropolis in high dimensional spaces and can be used easily when the proposal distribution is Gaussian. We explore the use of quasi Monte Carlo (QMC) methods to generate highly stratified samples. A series of examples is presented to evaluate the potential of the method.     

Minimum contrast estimation of random processes based on information of second and third orders

This paper presents the results on consistency and asymptotic normality of a class of minimum contrast estimators for random processes with short- or long-range dependence based on the second- and third-order cumulant spectra. Asymptotic properties of sample spectral functionals of second and third orders, which are of independent interest in view of their possible use for nonparametric estimation of processes with short- or long-range dependence, are also provided.     

INSIGHTS ON SERVICE SYSTEM DESIGN FROM A NORMAL APPROXIMATION TO ERLANG'S DELAY FORMULA

We show how a simple normal approximation to Erlang's delay formula can be used to analyze capacity and staffing problems in service systems that can be modeled as M/M/s queues. The numbers of servers, s, needed in an M/M/s queueing system to assure a probability of delay of, at most, p can be well approximated by s ≅ p + z_***I-p+, where z_1-p, is the (1 - p)th percentile of the standard normal distribution and ρ, the presented load on the system, is the ratio of Λ, the customer arrival rate, to μ, the service rate. We examine the accuracy of this approximation over a set of parameters typical of service operations ranging from police patrol, through telemarketing to automatic teller machines, and we demonstrate that it tends to slightly underestimate the number of servers actually needed to hit the delay probability target—adding one server to the number suggested by the above formula typically gives the exact result. More importantly, the structure of the approximation promotes operational insight by explicitly linking the number of servers with server utilization and the customer service level. Using a scenario based on an actual teleservicing operation, we show how operations managers and designers can quickly obtain insights about the trade-offs between system size, system utilization and customer service. We argue that this little used approach deserves a prominent role in the operations analyst's and operations manager's toolbags.     

Stochastic models for fractal processes

This paper considers the situation where a stochastic process may display both long-range dependence (LRD) and intermittency. The existence of such a process is established in Anh et al. (1999). Existing works have commonly paid attention either to LRD or intermittency quite separately. This paper offers a convenient framework to study both effects simultaneously. A method is given to estimate and separate the two effects. The wavelet theory plays an essential role in this procedure. Numerical experiments on fractional Brownian motion and multiplicative cascade processes confirm the power of the method.     

A study of three-dimensional curves

In certain abnormalities of spinal shape, the long axis of the spine moves out of the median sagittal plane, producing both an axial torsion and a lateral deviation out of the usual front-back plane. Clinicians need to be able to assess rapidly and accurately whether or not an individual has such an abnormality. In this paper, we examine several case studies. These are analyzed using some simple summary statistics, and the use of these methods to infer abnormality is demonstrated. Using a simple fitted model for the data, an angular estimate of abnormality is obtained. Empirical measures of abnormality based on the eigenvalues of the covariance matrix are also determined. These methods are applied to a number of individuals for whom the surface spinal profiles have been recorded and who have been assessed as normal or abnormal by clinicians.     

Student views on campus sexual assault

Abstract

Objective: To report on college student opinions about the scope of college sexual misconduct (CSM), suggested university sanctions, and treatment of students found responsible of CSM.

Participants: In all, 23?US undergraduate students (14 females and 9 males) with a mean age of 20 years.

Methods: Students participated either in female, male, or mixed-sex focus groups that facilitated the discussion of factors related to CSM.

Results: Students provided in-depth feedback on the climate on US college campuses and factors related to CSM. They agreed upon CSM risk factors and context characteristics, but raised different male and female issues across sex groups. They further provided resolute suggestions for the solution of CSM, experienced treatment barriers, and limited victim reporting.

Conclusion: Student focus groups provide important information about the scope of CSM and offer valuable suggestions for the solution of the problem that may be crucial for the development of successful sexual assault interventions.     

Correlates of depression in self-neglecting older adults: A cross-sectional study examining the role of alcohol abuse and pain in increasing vulnerability

ABSTRACT

Self-neglect among older adults results in increased morbidity and mortality rates. Depression is strongly linked to self-neglect and when untreated, severely complicates management of health and functional outcomes. The study aims to identify factors correlated with depression to inform approaches to service recruitment and retention that improve long-term outcomes. The sample included urban community-dwelling older adults (n = 96) 65 years of age and older with Adult Protective Services-substantiated self-neglect. All participants completed a range of validated cognitive, functional, and self-report demographic and clinical measures around health and mental health functioning. A secondary data analysis using multivariable logistic regression revealed that a positive screen for alcohol abuse, low self-rated health, and higher self-reported pain were associated with significantly higher odds of self-reported depression. Further research is needed to understand the temporality between these correlates and depression and to inform prevention and intervention practices for self-neglecting older adults.     

The passage,settlement, and occupational characteristics of Louisiana's Italian immigrants

This paper explores the general pattern of Italian immigration to Louisiana and describes the occupational attributes of the immigrants in five settlements in the state. The data indicate that unlike the national scene Italian immigration to Louisiana peaked before the 20th century and drew immigrants mainly from Sicily. The great majority of these immigrants were recruited for work on the sugar plantations of southern Louisiana. However, in New Orleans the majority soon became small merchants involved in every aspect of the food industry. This comparatively rapid entrance of Sicilian peasants into the lower ranks of the middle class is explained by the size of the immigrant population, by their distinctive cultural values and social experiences in southern Italy and Sicily, by the custom of gambling, and by the friendly compatability of the host culture in southern Louisiana. Also, tight incontestable family loyalties, hard work, and the custom of thrift made it possible for these economic individualists to make their niche in the social and economic life of Louisiana.     

Sex Differences Among College Students in Awareness of the Human Papillomavirus Vaccine and Vaccine Options

Abstract

Objectives: To explore awareness of human papillomavirus (HPV) and use of HPV vaccines (Gardasil and Cervarix) by college students. Participants: The sample was composed of 817 undergraduates at 2 northeastern US universities; they participated between February and May 2010. Methods: Students were provided with a link to an anonymous, self-administered, Web-based survey comprised of 76 questions. The survey included questions about health behaviors, awareness, and knowledge of HPV and the 2 HPV vaccines, and vaccine uptake. Results: Results indicate high levels of awareness of HPV as well as marked sex differences related to vaccine awareness and uptake. Both sexes are largely unaware of Cervarix and the differences between Cervarix and Gardasil. Conclusion: The study affirms the importance of a clinician's recommendation for HPV vaccination. Public health messaging should become more inclusive of adolescent and young adult males. College students’ awareness of HPV vaccine options mirrors Gardasil's market dominance in the United States.     

Social Relationships of African American and Hispanic Older Assisted Living Residents: Exploring the Role of Race and Ethnicity

African American and Hispanic older adults are underrepresented in assisted living communities, so little is known about how they experience social relationships in these settings. The purpose of the study was to explore resident-to-resident and resident-to-staff relationships experienced and perceived by African American and Hispanic older residents in assisted living settings. In-depth interviews with 15 African American and 15 Hispanic older adults were conducted in seven assisted living communities in Central Florida. Three salient themes emerged using a grounded theory approach: formation of relationships: emotional vs. instrumental support; language as a facilitator or barrier; and avoidance of inter-racial relationships. Implications for providing culturally competent services in assisted living communities with diverse populations are discussed.