Sample Size in Ordinal Logistic Hierarchical Linear Modeling

Most quantitative research is conducted by randomly selecting members of a population on which to conduct a study. When statistics are run on a sample, and not the entire population of interest, they are subject to a certain amount of error. Many factors can impact the amount of error, or bias, in statistical estimates. One important factor is sample size; larger samples are more likely to minimize bias than smaller samples. Therefore, determining the necessary sample size to obtain accurate statistical estimates is a critical component of designing a quantitative study. Much research has been conducted on the impact of sample size on simple statistical techniques such as group mean comparisons and ordinary least squares regression. Less sample size research, however, has been conducted on complex techniques such as hierarchical linear modeling (HLM). HLM, also known as multilevel modeling, is used to explain and predict an outcome based on knowledge of other variables in nested populations. Ordinal logistic HLM (OLHLM) is used when the outcome variable has three or more ordered categories. While there is a growing body of research on sample size for two-level HLM utilizing a continuous outcome, there is no existing research exploring sample size for OLHLM. The purpose of this study was to determine the impact of sample size on statistical estimates for ordinal logistic hierarchical linear modeling. A Monte Carlo simulation study was used to investigate this research query. Four variables were manipulated: level-one sample size, level-two sample size, sample outcome category allocation, and predictor-criterion correlation. Statistical estimates explored include bias in level-one and level-two parameters, power, and prediction accuracy. Results indicate that, in general, holding other conditions constant, bias decreases as level-one sample size increases. However, bias increases or remains unchanged as level-two sample size increases, holding other conditions constant. Power to detect the independent variable coefficients increased as both level-one and level-two sample size increased, holding other conditions constant. Overall, prediction accuracy is extremely poor. The overall prediction accuracy rate across conditions was 47.7%, with little variance across conditions. Furthermore, there is a strong tendency to over-predict the middle outcome category

Fool Me Once, Shame on Me; Fool Me Again and You\u27re Gonna Pay For It: An Analysis of Medicare\u27s New Reporting Requirements for Primary Payers and the Stiff Penalties Associated with Noncompliance

This article discusses the new requirements and the issues that currently face insurers, claimants, and attorneys in cases involving Medicare-eligible beneficiaries

Product Liability Law

While Virginia is not typically seen as progressive in the field of product liability law, the Commonwealth is nonetheless a forum in which these product liability battles take place. This article summarizes selected decisions of the United States Court of Appeals for the Fourth Circuit, federal district courts in Virginia, and courts of the Commonwealth issued between July 1, 2004 and May 15, 2005. This article also includes a discussion of the most relevant legislative changes made by the Virginia General Assembly over the same time period. While a complete analysis of every decision and statute affecting product liability is not possible, this article summarizes those which should be the most useful to practitioners in Virginia

Rites and Passages

&nbsp; Diabetes is a disease of control. Of ritual. Of measurement and limitations. Of repetition. Of unconscious results of conscious decision. Of trying to find freedom within the perimeters of disease and treatment. I have lived battling it all my life. It influences all that I do. Living with it is like walking a tightrope. Either side is death: too much or too little. One can never leave it. Yet to stay on it is so hard. Perfection is expected. Perfection is never achieved. Diabetics tend to die at an early age. My work is influenced by this fact of my life, and at times addresses it directly. Both the book Existence and the sculpture Diabetes: Path of Least Resistance speak of just a small part of being a diabetic. The book is a journal of one month of blood tests and insulin dosages, and the resultant blood sugar levels throughout the day. One schooled in diabetes understands the rituals the book portrays. One unfamiliar with the disease sees a record of the ritual of my daily existence; an obsessive repetition, like a heartbeat, only conscious. Dealt with daily it becomes a fact of life, almost unconscious, and thus a ritual of security as well as survival. One identifies with the disease and its daily care. The sculpture is confrontational: it forces the viewer to confront it, as a diabetic, or anyone with a chronic disease, must confront that disease every day of their lives. One cannot move across the gallery without either stepping over the piece or moving around it; a diabetic cannot face a moment without having to cope with the disease. The sculpture is made of three balancing beams, symbols of the "tightrope of control" one must walk as a diabetic. The urine testing cups full of sugar on one side of the beams refer to the effects of being "out of control," having too much sugar in the bloodstream(which then "spills" into a diabetics urine, filling it with sugar), a sure means of death to a diabetic. The cups with the ashes in them refer to the opposite effect, that of having too little sugar in the bloodstream, another sure means of death to one with the disease. The beams are 1 O" high, an uncomfortable height to step over, as diabetes is often an uncomfortable disease to live with. They act as a barrier in the gallery, as diabetes is often a barrier to certain aspects of life. Following along the piece, walking down its length, is therefore the "path of least resistance," a difficult and limiting path to walk, but actually the one that is the easiest to follow. </p

Strategies and barriers to achieving the goal of Finland’s tobacco endgame

ObjectivesFinland boldly legislated the end of tobacco use in its 2010 Tobacco Act, and subsequently expanded the goal in 2016 to eradicate other nicotine-containing products. This study explored stakeholders' perceptions about the strengths, barriers, solutions and rationale for Finland's comprehensive but conventional strategy to achieve its nicotine-free goal.DesignStudy participants were selected based on expertise in policy or practice of tobacco control (n=32). Semi-structured interviews, conducted in 2017 and 2018, covered topics ranging from consensus among stakeholders to Finland's ranking on the 2016 Tobacco Control Scale. The framework method was chosen for analysing interview transcripts.ResultsA perceived strength of Tobacco-Free Finland 2030 was the consensus and cooperation among members of the tobacco control community. The objective of becoming a nicotine- versus smoke-free society had almost unanimous support, challenged by a small minority who argued for greater discussion of harm reduction approaches. The need for maintaining legitimacy and historical successes in tobacco control were reasons for using a conventional strategy. Barriers to achieving the endgame goal included insufficient funding and over-reliance on non-governmental organisations, political/legal constraints, impact of institutional practices on tobacco disparities, ambivalence about the role of mass media and lack of prioritising smoking cessation.ConclusionsStakeholders' broad confidence in reaching the goal of Finland's tobacco endgame suggests that future policy initiatives will reflect the current, conventional strategy. If the Finnish government chooses to continue this approach, then it should designate separate funds for Tobacco-Free Finland 2030 and implement structural changes that will facilitate tobacco control initiatives

Comparing periodic-orbit theory to perturbation theory in the asymmetric infinite square well

An infinite square well with a discontinuous step is one of the simplest systems to exhibit non-Newtonian ray-splitting periodic orbits in the semiclassical limit. This system is analyzed using both time-independent perturbation theory (PT) and periodic-orbit theory and the approximate formulas for the energy eigenvalues derived from these two approaches are compared. The periodic orbits of the system can be divided into classes according to how many times they reflect from the potential step. Different classes of orbits contribute to different orders of PT. The dominant term in the second-order PT correction is due to non-Newtonian orbits that reflect from the step exactly once. In the limit in which PT converges the periodic-orbit theory results agree with those of PT, but outside of this limit the periodic-orbit theory gives much more accurate results for energies above the potential step.Comment: 22 pages, 2 figures, 2 tables, submitted to Physical Review