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4,945 full-text articles. Page 1 of 104.

Functional Regression, Jeffrey S. Morris 2015 The University of Texas

Functional Regression, Jeffrey S. Morris

Jeffrey S. Morris

Functional data analysis (FDA) involves the analysis of data whose ideal units of observation are functions defined on some continuous domain, and the observed data consist of a sample of functions taken from some population, sampled on a discrete grid. Ramsay and Silverman's 1997 textbook sparked the development of this field, which has accelerated in the past 10 years to become one of the fastest growing areas of statistics, fueled by the growing number of applications yielding this type of data. One unique characteristic of FDA is the need to combine information both across and within functions, which Ramsay ...


Statistical Inference For The Mean Outcome Under A Possibly Non-Unique Optimal Treatment Strategy, Alexander R. Luedtke, Mark J. van der Laan 2014 COBRA

Statistical Inference For The Mean Outcome Under A Possibly Non-Unique Optimal Treatment Strategy, Alexander R. Luedtke, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

We consider challenges that arise in the estimation of the value of an optimal individualized treatment strategy defined as the treatment rule that maximizes the population mean outcome, where the candidate treatment rules are restricted to depend on baseline covariates. We prove a necessary and sufficient condition for the pathwise differentiability of the optimal value, a key condition needed to develop a regular asymptotically linear (RAL) estimator of this parameter. The stated condition is slightly more general than the previous condition implied in the literature. We then describe an approach to obtain root-n rate confidence intervals for the optimal value ...


Modeling Count Data; Errata And Comments, Joseph M. Hilbe 2014 SelectedWorks

Modeling Count Data; Errata And Comments, Joseph M. Hilbe

Joseph M Hilbe

Modeling Count Data: Errata and Comments PDF. Will be updated on a continuing basis.


Mdc-R-Code, Joseph M. Hilbe 2014 SelectedWorks

Mdc-R-Code, Joseph M. Hilbe

Joseph M Hilbe

Modeling Count Data: R code for download and use.


Optimal, Two Stage, Adaptive Enrichment Designs For Randomized Trials Using Sparse Linear Programming, Michael Rosenblum, Xingyuan Fang, Han Liu 2014 COBRA

Optimal, Two Stage, Adaptive Enrichment Designs For Randomized Trials Using Sparse Linear Programming, Michael Rosenblum, Xingyuan Fang, Han Liu

Johns Hopkins University, Dept. of Biostatistics Working Papers

Adaptive enrichment designs involve preplanned rules for modifying enrollment criteria based on accruing data in a randomized trial. Such designs have been proposed, for example, when the population of interest consists of biomarker positive and biomarker negative individuals. The goal is to learn which populations benefit from an experimental treatment. Two critical components of adaptive enrichment designs are the decision rule for modifying enrollment, and the multiple testing procedure. We provide the first general method for simultaneously optimizing both of these components for two stage, adaptive enrichment designs. We minimize expected sample size under constraints on power and the familywise ...


Higher-Order Targeted Minimum Loss-Based Estimation, Marco Carone, Iván Díaz, Mark J. van der Laan 2014 COBRA

Higher-Order Targeted Minimum Loss-Based Estimation, Marco Carone, Iván Díaz, Mark J. Van Der Laan

U.C. Berkeley Division of Biostatistics Working Paper Series

Common approaches to parametric statistical inference often encounter difficulties in the context of infinite-dimensional models. The framework of targeted maximum likelihood estimation (TMLE), introduced in van der Laan & Rubin (2006), is a principled approach for constructing asymptotically linear and efficient substitution estimators in rich infinite-dimensional models. The mechanics of TMLE hinge upon first-order approximations of the parameter of interest as a mapping on the space of probability distributions. For such approximations to hold, a second-order remainder term must tend to zero sufficiently fast. In practice, this means an initial estimator of the underlying data-generating distribution with a sufficiently large rate ...


Confidence Intervals For The Treatment Effect On The Treated, José A. Ferreira 2014 COBRA

Confidence Intervals For The Treatment Effect On The Treated, José A. Ferreira

COBRA Preprint Series

The average effect of the treatment on the treated is a quantity of interest in observational studies in which no definite parameter can be used to quantify the treatment effect, such as those where only a random subset of the data obtained by stratification can be used for analysis. Non-parametric confidence intervals for this quantity appear to be known only in the case where the responses to the treatment are binary and the data fall into a single stratum. We propose nonparametric confidence intervals for the average effect of the treatment on the treated in studies involving one or more ...


Access To Hiv Prevention And Care For Hiv-Exposed And Hiv-Infected Children: A Qualitative Study In Rural And Urban Mozambique, Caroline de Schacht, Carlota Lucas, Caterina Mboa, Michelle Gill, Eugenia Macasse, Stelio A. Dimande, Emily A. Bobrow, Laura Guay 2014 Himmelfarb Health Sciences Library, The George Washington University

Access To Hiv Prevention And Care For Hiv-Exposed And Hiv-Infected Children: A Qualitative Study In Rural And Urban Mozambique, Caroline De Schacht, Carlota Lucas, Caterina Mboa, Michelle Gill, Eugenia Macasse, Stelio A. Dimande, Emily A. Bobrow, Laura Guay

Epidemiology and Biostatistics Faculty Publications

Background Follow-up of HIV-exposed children for the delivery of prevention of mother-to-child transmission services and for early diagnosis and treatment of HIV infection is critical to their survival. Despite efforts, uptake of postnatal care for these children remains low in many subSaharan African countries. Methods A qualitative study was conducted in three provinces in Mozambique to identify motivators and barriers to improve uptake of and retention in HIV prevention, care and treatment services for HIV-exposed and HIV-infected children. Participant recommendations were also gathered. Individual interviews (n=79) and focus group discussions (n=32) were conducted with parents/caregivers, grandmothers, community ...


A Vegetation Analysis On Horn Island, Mississippi, Ca. 1940 Using Characteristic Dimensions Derived From Historical Aerial Photography, Guy Wilburn Jeter Jr. 2014 The University of Southern Mississippi

A Vegetation Analysis On Horn Island, Mississippi, Ca. 1940 Using Characteristic Dimensions Derived From Historical Aerial Photography, Guy Wilburn Jeter Jr.

Master's Theses

Horn Island is part of the MS/AL barrier island chain in the northern Gulf of Mexico located approximately 18kn off the coast of Mississippi. This island’s habitats have undergone many transitions over the last several decades. The goal of this study was to quantify habitat change over a seventy year period using historical black and white photography from 1940. Using present NAIP imagery from the USDA, habitat structure was estimated by using geo-statistics, and second order statistics, from a co-occurrence matrix, to characterize texture for habitat classification. Percent land cover was then calculated to determine overall land cover ...


Prognostic Value Of Lymphocyte Vascular Density And E-Cadherin In Inflammatory Breast Cancer, Paul H. Levine, Heather J. Hoffman, Audra MacNeil, Salman Hashmi, Sherry X. Yang, Stephen Hewitt, Kenneth L. van Golen, Sandra M. Swain 2014 Himmelfarb Health Sciences Library, The George Washington University

Prognostic Value Of Lymphocyte Vascular Density And E-Cadherin In Inflammatory Breast Cancer, Paul H. Levine, Heather J. Hoffman, Audra Macneil, Salman Hashmi, Sherry X. Yang, Stephen Hewitt, Kenneth L. Van Golen, Sandra M. Swain

Epidemiology and Biostatistics Faculty Publications

Background: We recently evaluated four laboratory assays, vascular endothelial growth factor D (VEGF-D), E-cadherin, lymphatic vessel density (LVD) measured by podoplanin, and intra-lymphatic tumor emboli (ILTE), which showed notable differences between inflammatory breast cancer (IBC) and non-inflammatory locally advanced breast cancer (LABC). In this study we investigated the potential of the three most quantitatively measured markers, E-cadherin, LVD and VEGF-D, to predict survival in the IBC patients.

Materials and Methods: This study involved the 100 cases identified in the Inflammatory Breast Cancer Registry (IBCR) whose tumors were previously evaluated for the four assays noted above. Living patients were recontacted and ...


Identifying Change Points In A Covariate Effect On Time-To-Event Analysis With Reduced Isotonic Regression, Yong Ma, Yinglei Lai, John M. Lachin 2014 Himmelfarb Health Sciences Library, The George Washington University

Identifying Change Points In A Covariate Effect On Time-To-Event Analysis With Reduced Isotonic Regression, Yong Ma, Yinglei Lai, John M. Lachin

GW Biostatistics Center Faculty Publications

Isotonic regression is a useful tool to investigate the relationship between a quantitative covariate and a time-to-event outcome. The resulting non-parametric model is a monotonic step function of a covariate X and the steps can be viewed as change points in the underlying hazard function. However, when there are too many steps, over-fitting can occur and further reduction is desirable. We propose a reduced isotonic regression approach to allow combination of small neighboring steps that are not statistically significantly different. In this approach, a second stage, the reduction stage, is integrated into the usual monotonic step building algorithm by comparing ...


Doubly Robust Learning For Estimating Individualized Treatment With Censored Data, Ying-Qi Zhao, Donglin Zeng, Eric B. Laber, Rui Song, Ming Yuan, Michael R. Kosorok 2014 COBRA

Doubly Robust Learning For Estimating Individualized Treatment With Censored Data, Ying-Qi Zhao, Donglin Zeng, Eric B. Laber, Rui Song, Ming Yuan, Michael R. Kosorok

The University of North Carolina at Chapel Hill Department of Biostatistics Technical Report Series

Individualized treatment rules recommend treatments based on individual patient characteristics in order to maximize clinical benefit. When the clinical outcome of interest is survival time, estimation is often complicated by censoring. We develop nonparametric methods for estimating an optimal individualized treatment rule in the presence of censored data. To adjust for censoring, we propose a doubly robust estimator which requires correct specification of either the censoring model or survival model, but not both; the method is shown to be Fisher consistent when either model is correct. Furthermore, we establish the convergence rate of the expected survival under the estimated optimal ...


Viewing The Moon In Infrared, Kyle Beekman 2014 California Polytechnic State University

Viewing The Moon In Infrared, Kyle Beekman

Statistics

Man has been fascinated by the heavens since ancient times, yet there is still so much that we don’t know. This project was created by Dr. Gary Hughes with goal of obtaining information about the moon and other objects in the vicinity of the Earth. The project was mostly experimental in nature and there was no specific goal at the outset of the project. In the end the project focused on the moon and meteors that traveled through the Earth’s upper atmosphere. Throughout the month of August, students traveled to the Mount Barcroft Research Station in the Eastern ...


A Marginalized Zero-Inflated Negative Binomial Regression Model With Overall Exposure Effects, John S. Preisser, Kalyan Das, D. Leann Long, John W. Stamm 2014 COBRA

A Marginalized Zero-Inflated Negative Binomial Regression Model With Overall Exposure Effects, John S. Preisser, Kalyan Das, D. Leann Long, John W. Stamm

The University of North Carolina at Chapel Hill Department of Biostatistics Technical Report Series

The zero-inflated negative binomial regression model (ZINB) is often employed in diverse fields such as dentistry, health care utilization, highway safety, and medicine, to examine relationships between exposures of interest and overdispersed count outcomes exhibiting many zeros. The regression coefficients of ZINB have latent class interpretations for a susceptible subpopulation at risk for the disease/condition under study with counts generated from a negative binomial distribution and for a non-susceptible subpopulation that provides only zero counts. The ZINB parameters, however, are not well-suited for estimating overall exposure effects, specifically, in quantifying the effect of an explanatory variable in the overall ...


Visualizing Probabilistic Proof, Enrique Guerra-Pujol 2014 Washington University in St. Louis

Visualizing Probabilistic Proof, Enrique Guerra-Pujol

Washington University Jurisprudence Review

The author revisits the Blue Bus Problem, a famous thought-experiment in law involving probabilistic proof, and presents Bayesian solutions to different versions of the blue bus hypothetical. In addition, the author expresses his solutions in standard and visual formats, that is, in terms of probabilities and natural frequencies.


Mdc-R-Code, Joseph M. Hilbe 2014 SelectedWorks

Mdc-R-Code, Joseph M. Hilbe

Joseph M Hilbe

Modeling Count Data: R code in book provided for use


On The Restricted Mean Survival Time Curve Survival Analysis, Lihui Zhao, Brian Claggett, Lu Tian, Hajime Uno, Marc A. Pfeffer, Scott D. Solomon, Lorenzo Trippa, L. J. Wei 2014 COBRA

On The Restricted Mean Survival Time Curve Survival Analysis, Lihui Zhao, Brian Claggett, Lu Tian, Hajime Uno, Marc A. Pfeffer, Scott D. Solomon, Lorenzo Trippa, L. J. Wei

Harvard University Biostatistics Working Paper Series

No abstract provided.


Quantifying An Adherence Path-Specific Effect Of Antiretroviral Therapy In The Nigeria Pepfar Program, Caleb Miles, Ilya Shpitser, Phyllis Kanki, Seema Meloni, Eric J. Tchetgen Tchetgen 2014 COBRA

Quantifying An Adherence Path-Specific Effect Of Antiretroviral Therapy In The Nigeria Pepfar Program, Caleb Miles, Ilya Shpitser, Phyllis Kanki, Seema Meloni, Eric J. Tchetgen Tchetgen

Harvard University Biostatistics Working Paper Series

No abstract provided.


Top Of The Order: Modeling The Optimal Locations Of Minor League Baseball Teams, W. Coleman Conley 2014 Illinois Wesleyan University

Top Of The Order: Modeling The Optimal Locations Of Minor League Baseball Teams, W. Coleman Conley

Undergraduate Economic Review

Over the last twenty-five years, minor league baseball franchises have defined firm mobility. Revisiting the work of Michael C. Davis (2006), I construct a logistic regression model to predict which cities house minor league baseball teams. Six variables are tested for inclusion in the model, including population, income level, the number of major-league professional sports teams in a city, five-year population change, and distance from the closest professional team. Based on the model's predicted probabilities, cities are ranked in order of highest probability of having a team at each of the different levels from Class A to Class AAA.


Negative Binomial Regerssion, 2nd Ed, 2nd Print, Errata And Comments, Joseph Hilbe 2014 SelectedWorks

Negative Binomial Regerssion, 2nd Ed, 2nd Print, Errata And Comments, Joseph Hilbe

Joseph M Hilbe

Errata and Comments for 2nd printing of NBR2, 2nd edition. Previous errata from first printing all corrected. Some added and new text as well.


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