Physical Sciences and Mathematics Commons^™

Exact One-Sided Confidence Limits For The Difference Between Two Correlated Proportions, Chris Lloyd, Max V. Moldovan

Chris J. Lloyd

We construct exact and optimal one-sided upper and lower confidence bounds for the difference between two probabilities based on matched binary pairs using well-established optimality theory of Buehler (1957). Starting with five different approximate loer and upper limits, we adjust them to have coverage probability exactly equal to the desired nominal level and then compare the resulting exact limits by their mean size. Exact limits based on the signed root likelihood ratio statistic are preferred and recommended for practical use.

Correction: Using Participatory Design To Develop (Public) Health Decision Support Systems Through Gis, S. Michelle Driedger, Anita Kothari, Jason Morrison, Michael Sawada, Eric J. Crighton, Ian D. Graham

Anita Kothari

Background: Organizations that collect substantial data for decision-making purposes are often characterized as being 'data rich' but 'information poor'. Maps and mapping tools can be very useful for research transfer in converting locally collected data into information. Challenges involved in incorporating GIS applications into the decision-making process within the non-profit (public) health sector include a lack of financial resources for software acquisition and training for nonspecialists to use such tools. This on-going project has two primary phases. This paper critically reflects on Phase 1: the participatory design (PD) process of developing a collaborative web-based GIS tool.

Methods: A case study …

Functional Principal Component Regression And Functional Partial Least Squares, Philip T. Reiss, R. Todd Ogden

Philip T. Reiss

Regression of a scalar response on signal predictors, such as near-infrared (NIR) spectra of chemical samples, presents a major challenge when, as is typically the case, the dimension of the signals far exceeds their number. Most solutions to this problem reduce the dimension of the predictors either by regressing on components--e.g. principal component regression (PCR) and partial least squares (PLS)--or by smoothing methods which restrict the coefficient function to the span of a spline basis. This paper introduces functional versions of PCR and PLS, which combine both of the above dimension reduction approaches. Two versions of functional PCR are developed, …

A Large-Scale Rheumatoid Arthritis Genetic Study Identifies Association At Chr 9q33.2, Steven J. Schrodi

Steven J Schrodi

No abstract provided.

Chess, Chance And Conspiracy, Mark Segal

Mark R Segal

Chess and chance are seemingly strange bedfellows. Luck and/or randomness have no apparent role in move selection when the game is played at the highest levels. However, when competition is at the ultimate level, that of the World Chess Championship (WCC), chess and conspiracy are not strange bedfellows, there being a long and colorful history of accusations levied between participants. One such accusation, frequently repeated, was that all the games in the 1985 WCC (Karpov vs Kasparov) were fixed and prearranged move by move. That this claim was advanced by a former World Champion, Bobby Fischer, argues that it ought …

Software To Forecast The Global Burden Of Alzheimer's Disease, Ron Brookmeyer, Elizabeth Johnson, Kathryn Ziegler-Graham, H. Michael Arrighi

Ron Brookmeyer

Software was developed to forecast the global burden of Alzheimer’s disease and evaluate the potential impact of interventions that delay disease onset and progression. The output includes 50 year projections of Alzheimer's disease prevalence by stage of disease and region of the world. The methods are based on a stochastic multi-state model The software incorporates U.N. worldwide population forecasts and data from epidemiological studies on risks of Alzheimer’s disease. The user can also supply their own population projections, and modify input parameters for the model including the disease incidence rates, effects of interventions on disease onset and progression, and stages …

Confidence Intervals For Biomarker-Based Human Immunodeficiecny Virus Incidence Estimates And Differences Using Prevalent Data, Ron Brookmeyer, S Cole, H Chu

Ron Brookmeyer

Prevalent biological specimens can be used to estimate human immunodeficiency virus (HIV) incidence using a two-stage immunologic testing algorithm that hinges on the average time, say T, between testing HIV positive on highly and less sensitive enzyme immunoassays. Common approaches to confidence interval (CI) estimation for this incidence measure have included (1) ignoring the random error in T or (2) employing a Bonferroni adjustment to the box method. The authors present alternative Monte Carlo-based CIs for this incidence measure, as well as CIs for the biomarker-based incidence difference; standard approaches to CIs are typically appropriate for the incidence ratio. Using …

Modeling The Effect Of Alzheimer's Disease On Mortality, Elizabeth Johnson, Ron Brookmeyer, Kathryn Ziegler-Graham

Ron Brookmeyer

Mortality rate ratios and the associated proportional hazards models have been used to summarize the effect of Alzheimer's disease on longevity. However, the mortality rate ratios vary by age and therefore do not provide a simple parsimonious summary of the effect of the disease on lifespan. Instead, we propose a new parameter that is defined by an additive multistate model. The proposed multistate model accounts for different stages of disease progression. The underlying assumption of the model is that the effect of disease on mortality is to add a constant amount to death rates once the disease progresses from an …

A Practical Illustration Of The Importance Of Realistic Individualized Treatment Rules In Causal Inference, Oliver Bembom, Mark J. Van Der Laan

Oliver Bembom

The effect of vigorous physical activity on mortality in the elderly is difficult to estimate using conventional approaches to causal inference that define this effect by comparing the mortality risks corresponding to hypothetical scenarios in which all subjects in the target population engage in a given level of vigorous physical activity. A causal effect defined on the basis of such a static treatment intervention can only be identified from observed data if all subjects in the target population have a positive probability of selecting each of the candidate treatment options, an assumption that is highly unrealistic in this case since …