Using Exploratory Factor Analysis for Locating Invariant Referents in Factor Invariance Studies

Model identification in multi-group confirmatory factor analysis (MCFA) requires an equality constraint of referent variables across groups. Invariance assumption violations make it difficult to locate parameters that actually differ. Suggested procedures for locating invariant referents are cumbersome, complex, and provide imperfect results. Exploratory factor analysis (EFA) may be an alternative because of its ease of use, yet empirical evaluation of its effectiveness is lacking. EFAs accuracy for distinguishing invariant from non-invariant referents was examined

Comparing Factor Loadings in Exploratory Factor Analysis: A New Randomization Test

Factorial invariance testing requires a referent loading to be constrained equal across groups. This study introduces a randomization test for comparing group exploratory factor analysis loadings so as to identify an invariant referent. Results show that it maintains the Type I error rate while providing adequate power under most conditions

Parameter Estimation with Mixture Item Response Theory Models: A Monte Carlo Comparison of Maximum Likelihood and Bayesian Methods

The Mixture Item Response Theory (MixIRT) can be used to identify latent classes of examinees in data as well as to estimate item parameters such as difficulty and discrimination for each of the groups. Parameter estimation via maximum likelihood (MLE) and Bayesian estimation based on the Markov Chain Monte Carlo (MCMC) are compared for classification accuracy and parameter estimation bias for difficulty and discrimination. Standard error magnitude and coverage rates were compared across number of items, number of latent groups, group size ratio, total sample size and underlying item response model. Results show that MCMC provides more accurate group membership recovery across conditions and more accurate parameter estimates for smaller samples and fewer items. MLE produces narrower confidence intervals than MCMC and more accurate parameter estimates for larger samples and more items. Implications of these results for research and practice are discussed

Occurrence and habits of the Gambaga Flycatcher Muscicapa gambagae in Kenya, including the first description of its song

Historically, the Gambaga Flycatcher Muscicapa gambagae has been a relatively poorly known bird in Kenya. Following a review of all known records in Kenya, we show that breeding of presumed resident birds is known from three discreet areas, but that as many as 47% of all records, from the months of October to March, come from areas where breeding is not known. This finding indicates a migratory origin for these individuals, and the concurrent absence of northern, summer-breeding Gambaga Flycatchers from the mountainous regions of western Saudi Arabia, Yemen and northern Somalia point to that region as a likely origin of these winter visitors. Furthermore, records show that the frequency of occurrence of the Gambaga Flycatcher in Kenya is also increasing, with a rate of reporting since 2000 which is four times higher than during the period 1960–2000, likely representing a shift in range. Lastly, we also describe some habitat characteristics at preferred sites, and provide the first published sonograms and accompanying description of the song

Observation of low-lying isomeric states in 136^{136}Cs: a new avenue for dark matter and solar neutrino detection in xenon detectors

We report on new measurements establishing the existence of low-lying isomeric states in $^{136}$Cs using $\gamma$ rays produced in $^{136}$Xe(p,n)$^{136}$Cs reactions. Two states with $\mathcal{O}(100)$~ns lifetimes are placed in the decay sequence of the $^{136}$Cs levels that are populated in charged-current interactions of solar neutrinos and fermionic dark matter with $^{136}$Xe. Xenon-based experiments can therefore exploit a delayed-coincidence tag of these interactions, greatly suppressing backgrounds to enable spectroscopic studies of solar neutrinos and dark matter.Comment: Supplemental material available upon request. Version accepted by Phys.Rev.Let

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

A Model for Interprofessional Health Disparities Education: Student-Led Curriculum on Chronic Hepatitis B Infection

Although health disparities are commonly addressed in preclinical didactic curricula, direct patient care activities with affected communities are more limited. To address this problem, health professional students designed a preclinical service-learning curriculum on hepatitis B viral (HBV) infection, a major health disparity affecting the Asian/Pacific Islander (API) population, integrating lectures, skills training, and direct patient care at student-run clinics. An urban health professions campus. Medical and other health professional students at University of California, San Francisco, organized a preclinical didactic and experiential elective, and established two monthly clinics offering HBV screening, vaccination, and education to the community. Between 2004 and 2009, 477 students enrolled in the student-led HBV curriculum. Since the clinics’ inception in 2007, 804 patients have been screened for chronic HBV; 87% were API immigrants, 63% had limited English proficiency, and 46% were uninsured. Serologically, 10% were found to be chronic HBV carriers, 44% were susceptible to HBV, and 46% were immune. Our student-led didactic and experiential elective can serve as an interprofessional curricular model for learning about specific health disparities while providing important services to the local community

Treatment and Intervention for Opiate Dependence in the United Kingdom:Lessons from Triumph and Failure

The history of opiate treatment in the United Kingdom (UK) since the early 1980s is a rich source of learning about the benefits and pitfalls of drug treatment policy. We present five possible lessons to be learnt about how factors outside the clinic, including government, charities and researchers can influence treatment and outcomes. First, do not let a crisis go to waste. The philosophical shift from abstinence to harm reduction in the 1980s, in response to an HIV outbreak in injecting users, facilitated expansion in addiction services and made a harm reduction approach more acceptable. Second, studies of drug-related deaths can lead to advances in care. By elucidating the pattern of mortality, and designing interventions to address the causes, researchers have improved patient safety in certain contexts, though significant investment in Scotland has not arrested rising mortality. Third, collection of longitudinal data and its use to inform clinical guidelines, as pursued from the mid-1990s, can form an enduring evidence base and shape policy, sometimes in unintended ways. Fourth, beware of the presentation of harm reduction and recovery as in conflict. At the least, this reduces patient choice, and at worst, it has caused some services to be redesigned in a manner that jeopardises patient safety. Fifth, the relationship between the third and state sectors must be carefully nurtured. In the UK, early collaboration has been replaced by competition, driven by changes in funding, to the detriment of service provision