Statistics and Probability Commons^™

Controlling For Confounding Via Propensity Score Methods Can Result In Biased Estimation Of The Conditional Auc: A Simulation Study, Hadiza I. Galadima, Donna K. Mcclish

Community & Environmental Health Faculty Publications

In the medical literature, there has been an increased interest in evaluating association between exposure and outcomes using nonrandomized observational studies. However, because assignments to exposure are not random in observational studies, comparisons of outcomes between exposed and nonexposed subjects must account for the effect of confounders. Propensity score methods have been widely used to control for confounding, when estimating exposure effect. Previous studies have shown that conditioning on the propensity score results in biased estimation of conditional odds ratio and hazard ratio. However, research is lacking on the performance of propensity score methods for covariate adjustment when estimating the …

Package Development, Jason Klaassen, Randall Pruim

Summer Research

Project MOSAIC maintains several R packages that can be used by any R users. These users can suggest improvements and request new features. In addition, changes to dependency packages and the creation of new packages can require internal changes to the MOSAIC suite of packages. Unit testing is important to make sure that new features work as designed and that updates to packages do not break old behavior.

The main projects I worked on were:

• The mosaic package (updates and unit tests)
• The leaflethex package (new package)
• Lock5WithR Textbook Companion created with bookdown (revise and reformat)

The Dark Sky Character Of Archaeological Landscapes: Cultural Meaning And Conservation Strategies, Frank Prendergast

Book/Book Chapter

This paper presents the first ever study of light pollution at selected Irish prehistoric archaeological landscapes. The concepts of cosmology and landscape are first briefly described and followed by a summary of early human settlement of the island. Building on this, the extant corpus of early prehistoric megalithic burial tombs is illustrated to show their contrasting distribution patterns and typology. Analysis of tomb locations using nearest-neighbour statistical methods reveals evidence of intentional clustering. Further geo-statistical analysis identifies the geographical locations and the density ranking of these nucleated clusters - a feature especially evident in the passage tomb tradition on this …

How Can The Final Goal Of Completely Replacing Animal Procedures Successfully Be Achieved?, Christiane Baumgartl-Simons, Christiane Hohense

Validation of Alternative Methods Collection

Article 23 of European Union (EU) Directive 86/609/EEC required that Member States promote the development and validation of alternative technologies and stated that the European Commission (EC) “shall report before the end of 1987 on the possibility of modifying tests and guidelines” (European Parliament, 1986, Article 23). This Directive was replaced by Directive 2010/63/EU on the protection of animals used for scientific purposes, which now requires that Member States develop and validate alternative approaches much more precisely and specifies that the ultimate objective is the “full replacement of procedures on live animals for scientific and educational purposes, as soon as …

How To Evaluate The Science Of Non-Human Animal Use In Biomedical Research And Testing: A Proposed Format For Debate, Ray Greek, Lisa A. Kramer

Validation of Alternative Methods Collection

Over time, the interpretation of science has occasionally been corrupted by vested interest groups, be they financially motivated or ego driven. Scientific consensus and widespread public beliefs usually catch up with the evidence, but this can take a very long time and often costs lives. The use of non-human animals in biomedical research and testing is a scientific endeavor and, as such, can and should be evaluated in light of the best science currently available. But facts that have been accepted in all areas of science are routinely ignored or called into question by well-funded, vested interest groups, compromising the …

Extrapolation Of Animal Research Data To Humans: An Analysis Of The Evidence, Rebecca Ram

Validation of Animal Experimentation Collection

The ethical arguments against animal experimentation remain ever-strong. In addition, the scientific case against the use of animals in research grows more compelling, with exponential progress in the development of alternative methods and new research technologies. The Dutch authorities recently announced an ambitious, but welcome, proposal to phase out “the use of laboratory animals in regulatory safety testing of chemicals, food ingredients, pesticides and (veterinary) medicines” by 2025, as well as “the use of laboratory animals for the release of biological products, such as vaccines” (Netherlands National Committee for the protection of animals used for scientific purposes, NCad, 2016, p. …

Replacing Animal Tests To Improve Safety For Humans, Kathy Archibald, Robert Coleman, Tamara Drake

Application of Alternative Methods Collection

In this chapter, we propose a new, pragmatic approach that could accelerate the replacement of most, if not all, regulatory animal tests with superior tests based on human biology. We also propose that changes to the requirements for safety testing, issued by the us Food and Drug Administration (fda), must be made in order to enable the use of superior new tests, which are currently disadvantaged by the outdated language of the regulations. But first, it is imperative to establish some level of understanding of the efficacy of existing animal-based methods in order to know whether any possible replacement is …

The Changing Paradigm In Preclinical Toxicology: In Vitro And In Silico Methods In Liver Toxicity Evaluations, Fozia Noor

Application of Alternative Methods Collection

In vitro methods, based on human primary cells, cell lines, and genetically modified reporter cell lines, have greatly expanded the scope of in vitro toxicology. Other significant progress in the area of human-induced pluripotent stem cells (hiPSCs) (Asgari et al., 2010; Schwartz et al., 2014; Shinde et al., 2016; Shtrichman, Germanguz and Itskovitz-Eldor, 2013) is allowing the application of patient and disease-specific hiPSCs (Ghodsizadeh et al., 2010; McCracken et al., 2014; Siller et al., 2013). Moreover, the tools of precise genome editing with engineered nucleases, such as the zinc finger nucleases (zfns), the transcription activator-like effecter nucleases (talens) and, more …

The Potential Of Organ On Chip Technology For Replacing Animal Testing, Malcolm Wilkinson

Human Clinical Trials Collection

The term organ on a chip is used to describe the latest stage of development of in vitro cell culture technology. Figure 26.1 shows its steady development since the 1960s. Each step forward has improved our ability to model human-clinical response to new drugs or therapies and has enabled safety risk assessment of existing cosmetics, personal care products, or other chemicals in the environment. Scientific evidence that the predictive power of in vitro tests is superior to the use of animals will trigger a major shift in the way that medical research, in many areas, is carried out. In this …

Recent Developments In Alternatives To Animal Testing, Katy Taylor

Application of Alternative Methods Collection

Methods that replace techniques that use live animals, or methods of testing substances without live animal use, are known as alternatives, replacements or non-animal methods. Some prefer the term advanced technologies given the fact that they often rely on more sophisticated technology and are more human- relevant than the animal test they replace (see Langley et al., 2015). There have been efforts to replace animal tests since the 1960s. Significant progress initially came in replacing animals used to diagnose human disease; to produce biological drugs (such as vaccines); and to safety test batches of these drugs as they were produced. …

A Second Order Bdf Numerical Scheme With Variable Steps For The Cahn-Hilliard Equation, Wenbin Chen, Xiaoming Wang, Yue Yan, Zhuying Zhang

Mathematics and Statistics Faculty Research & Creative Works

We present and analyze a second order in time variable step BDF2 numerical scheme for the Cahn-Hilliard equation. the construction relies on a second order backward difference, convex-splitting technique and viscous regularizing at the discrete level. We show that the scheme is unconditionally stable and uniquely solvable. in addition, under mild restriction on the ratio of adjacent time-steps, an optimal second order in time convergence rate is established. the proof involves a novel generalized discrete Gronwall-type inequality. as far as we know, this is the first rigorous proof of second order convergence for a variable step BDF2 scheme, even in …

Be Wary Of Black-Box Trading Algorithms, Gary N. Smith

Pomona Economics

Black-box algorithms now account for nearly a third of all U. S. stock trades. It is a mistake to think that these algorithms possess superhuman intelligence. In reality, computers do not have the common sense and wisdom that humans have accumulated by living. Trading algorithms are particularly dangerous because they are so efficient at discovering statistical patterns—but so utterly useless in judging whether the discovered patterns are meaningful.

The Paradox Of Big Data, Gary N. Smith

Pomona Economics

Data-mining is often used to discover patterns in Big Data. It is tempting believe that because an unearthed pattern is unusual it must be meaningful, but patterns are inevitable in Big Data and usually meaningless. The paradox of Big Data is that data mining is most seductive when there are a large number of variables, but a large number of variables exacerbates the perils of data mining.

Outcome Prediction In Intensive Care Unit Settings With Claims Data, Lauren Staples, Ryan Rimby

Published and Grey Literature from PhD Candidates

The MIMIC III data comes from an Intensive Care Unit in Boston over a period of 10 years. This data contains billing codes as well as lab and demographic data. This project predicts the outcome “death within 30 days of discharge” through the lense of a healthcare billing company, to see if healthcare companies can play a role in healthcare quality, by only using data that they would have access to (billing and demographic data). This project used a unique method of nominal data variable reduction specific to ICD 9 and CPT codes, and compared the performance of logistic regression …

The Scaling Limit Of The Membrane Model, Alessandra Cipriani, Biltu Dan, Rajat Subhra Hazra

Journal Articles

On the integer lattice, we consider the discrete membrane model, a random interface in which the field has Laplacian interaction. We prove that, under appropriate rescaling, the discrete membrane model converges to the continuum membrane model in d ≥ 2. Namely, it is shown that the scaling limit in d = 2, 3 is a Holder continuous random field, while in d ≥ 4 the membrane model converges to a random distribution. As a by-product of the proof in d = 2, 3, we obtain the scaling limit of the maximum. This work complements the analogous results of Caravenna and …

The Effect Of Exemplar Likability On Moral Elevation, Nathan Lefebre, Peter Meindl

Summer Research

• “Moral elevation,” the emotional response to exceptional virtue, increases prosocial behavior (Thompson & Siegel, 2017).
• We examined the effect of actors’ morallyirrelevant characteristics (namely, likability) on elevation levels.
• Despite an effective manipulation, participants in the likable condition did not significantly differ from the control condition
• Perhaps counterintuitively, this suggests that exemplar likability does not have a direct effect on feelings of moral elevation.

10. Corrections To Design And Analysis Of Experiments, Angela Dean, Dan Voss, Danel Draguljic

Design and Analysis of Experiments

Corrections for the provided by the authors for Design and Analysis of Experiments.

An Information Theory-Based Approach To Assessing Spatial Patterns In Complex Systems, Tarsha Eason, Wen Ching-Chuang, Shana Sundstrom, Heriberto Cabezas

School of Natural Resources: Faculty Publications

Given the intensity and frequency of environmental change, the linked and cross-scale nature of social-ecological systems, and the proliferation of big data, methods that can help synthesize complex system behavior over a geographical area are of great value. Fisher information evaluates order in data and has been established as a robust and effective tool for capturing changes in system dynamics, including the detection of regimes and regime shifts. The methods developed to compute Fisher information can accommodate multivariate data of various types and requires no a priori decisions about system drivers, making it a unique and powerful tool. However, the …

Time Series Forecasting And Analysis: A Study Of American Clothing Retail Sales Data, Weijun Huang

Honors Undergraduate Theses

This paper serves to address the effect of time on the sales of clothing retail, from 2010 to May 2019. The data was retrieved from the US Census, where N=113 observations were used, which were plotted to observe their trends. Once outliers and transformations were performed, the best model was fit, and diagnostic review occurred. Inspections for seasonality and forecasting was also conducted. The final model came out to be an ARIMA (2,0,1). Slight seasonality was present, but not enough to drastically influence the trends. Our results serve to highlight the economic growth of clothing retail sales for the past …

An Examination Of Computational Methods Related To G/M/C Queueing, Thomas Michaud Ms

All Student Scholarship

The following examination of computational methods related to queues with general arrivals (i:i:d: but of unknown distribution), multiple identical servers with i:i:d: exponential service times, and ordinary first come, first served service (hereafter referred to as G/M/c to use existing naming conventions) seeks to investigate the current models and provide new results based on a draft convolution method proposed by El-Taha[3]. The new model will demonstrate the use of distributions with coefficients of variance ranging from zero to near infinity to provide flexibility in simulating a range of potential arrival distributions, and we include detailed results and software for both …