Open Access. Powered by Scholars. Published by Universities.®

2008

Discipline
Institution
Keyword
Publication
Publication Type

Articles 1 - 15 of 15

Full-Text Articles in Longitudinal Data Analysis and Time Series

Corso Di Analisi Delle Serie Storiche A.A 2008/2009- Laboratorio Di Stata: Lezione 3 –Analisi Classica Delle Serie Storiche I (Formato Pdf), Carlo Drago Dec 2008

Corso Di Analisi Delle Serie Storiche A.A 2008/2009- Laboratorio Di Stata: Lezione 3 –Analisi Classica Delle Serie Storiche I (Formato Pdf), Carlo Drago

Carlo Drago

No abstract provided.


Bayesian Model Averaging For Clustered Data: Imputing Missing Daily Air Pollution Concentration, Howard H. Chang, Francesca Dominici, Roger D. Peng Dec 2008

Bayesian Model Averaging For Clustered Data: Imputing Missing Daily Air Pollution Concentration, Howard H. Chang, Francesca Dominici, Roger D. Peng

Johns Hopkins University, Dept. of Biostatistics Working Papers

The presence of missing observations is a challenge in statistical analysis especially when data are clustered. In this paper, we develop a Bayesian model averaging (BMA) approach for imputing missing observations in clustered data. Our approach extends BMA by allowing the weights of competing regression models for missing data imputation to vary between clusters while borrowing information across clusters in estimating model parameters. Through simulation and cross-validation studies, we demonstrate that our approach outperforms the standard BMA imputation approach where model weights are assumed to be the same for all clusters. We then apply our proposed method to a national …


Corso Di Analisi Delle Serie Storiche A.A 2008/2009- Laboratorio Di Stata: Lezione 2 - Costruzione Di Datasets Temporali, Trasformazioni E Analisi Grafica (Formato Pdf), Carlo Drago Dec 2008

Corso Di Analisi Delle Serie Storiche A.A 2008/2009- Laboratorio Di Stata: Lezione 2 - Costruzione Di Datasets Temporali, Trasformazioni E Analisi Grafica (Formato Pdf), Carlo Drago

Carlo Drago

No abstract provided.


Spatial Misalignment In Time Series Studies Of Air Pollution And Health Data, Roger D. Peng, Michelle L. Bell Dec 2008

Spatial Misalignment In Time Series Studies Of Air Pollution And Health Data, Roger D. Peng, Michelle L. Bell

Johns Hopkins University, Dept. of Biostatistics Working Papers

Time series studies of environmental exposures often involve comparing daily changes in a toxicant measured at a point in space with daily changes in an aggregate measure of health. Spatial misalignment of the exposure and response variables can bias the estimation of health risk and the magnitude of this bias depends on the spatial variation of the exposure of interest. In air pollution epidemiology, there is an increasing focus on estimating the health effects of the chemical components of particulate matter. One issue that is raised by this new focus is the spatial misalignment error introduced by the lack of …


Space-Time Regression Modeling Of Tree Growth Using The Skew-T Distribution, Farouk S. Nathoo Dec 2008

Space-Time Regression Modeling Of Tree Growth Using The Skew-T Distribution, Farouk S. Nathoo

COBRA Preprint Series

In this article we present new statistical methodology for the analysis of repeated measures of spatially correlated growth data. Our motivating application, a ten year study of height growth in a plantation of even-aged white spruce, presents several challenges for statistical analysis. Here, the growth measurements arise from an asymmetric distribution, with heavy tails, and thus standard longitudinal regression models based on a Gaussian error structure are not appropriate. We seek more flexibility for modeling both skewness and fat tails, and achieve this within the class of skew-elliptical distributions. Within this framework, robust space-time regression models are formulated using random …


A Functional Random Effects Model For Flexible Assessment Of Susceptibility In Longitudinal Designs, Brent A. Coull Oct 2008

A Functional Random Effects Model For Flexible Assessment Of Susceptibility In Longitudinal Designs, Brent A. Coull

Harvard University Biostatistics Working Paper Series

No abstract provided.


Estimation In Semiparametric Transition Measurement Error Models For Longitudinal Data, Wenqin Pan, Donglin Zeng, Xihong Lin Sep 2008

Estimation In Semiparametric Transition Measurement Error Models For Longitudinal Data, Wenqin Pan, Donglin Zeng, Xihong Lin

Harvard University Biostatistics Working Paper Series

No abstract provided.


"%Qls Sas Macro: A Sas Macro For Analysis Of Longitudinal Data Using Quasi-Least Squares"., Hanjoo Kim, Justine Shults Aug 2008

"%Qls Sas Macro: A Sas Macro For Analysis Of Longitudinal Data Using Quasi-Least Squares"., Hanjoo Kim, Justine Shults

UPenn Biostatistics Working Papers

Quasi-least squares (QLS) is an alternative computational approach for estimation of the correlation parameter in the framework of generalized estimating equations (GEE). QLS overcomes some limitations of GEE that were discussed in Crowder (Biometrika 82 (1995) 407-410). In addition, it allows for easier implementation of some correlation structures that are not available for GEE. We describe a user written SAS macro called %QLS, and demonstrate application of our macro using a clinical trial example for the comparison of two treatments for a common toenail infection. %QLS also computes the lower and upper boundaries of the correlation parameter for analysis of …


Joint Spatial Modeling Of Recurrent Infection And Growth With Processes Under Intermittent Observation, Farouk S. Nathoo Aug 2008

Joint Spatial Modeling Of Recurrent Infection And Growth With Processes Under Intermittent Observation, Farouk S. Nathoo

COBRA Preprint Series

In this article we present new statistical methodology for longitudinal studies in forestry where trees are subject to recurrent infection and the hazard of infection depends on tree growth over time. Understanding the nature of this dependence has important implications for reforestation and breeding programs. Challenges arise for statistical analysis in this setting with sampling schemes leading to panel data, exhibiting dynamic spatial variability, and incomplete covariate histories for hazard regression. In addition, data are collected at a large number of locations which poses computational difficulties for spatiotemporal modeling. A joint model for infection and growth is developed; wherein, a …


On The Designation Of The Patterned Associations For Longitudinal Bernoulli Data: Weight Matrix Versus True Correlation Structure?, Hanjoo Kim, Joseph M. Hilbe, Justine Shults Jun 2008

On The Designation Of The Patterned Associations For Longitudinal Bernoulli Data: Weight Matrix Versus True Correlation Structure?, Hanjoo Kim, Joseph M. Hilbe, Justine Shults

UPenn Biostatistics Working Papers

Due to potential violation of standard constraints for the correlation for binary data, it has been argued recently that the working correlation matrix should be viewed as a weight matrix that should not be confused with the true correlation structure. We propose two arguments to support our view to the contrary for the first-order autoregressive AR(1) correlation matrix. First, we prove that the standard constraints are not unduly restrictive for the AR(1) structure that is plausible for longitudinal data; furthermore, for the logit link function the upper boundary value only depends on the regression parameter and the change in covariate …


Methods For The Analysis Of Developmental Respiration Patterns., Justin Tyler Peyton May 2008

Methods For The Analysis Of Developmental Respiration Patterns., Justin Tyler Peyton

Electronic Theses and Dissertations

This thesis looks at the problem of developmental respiration in Sarcophaga crassipalpis Macquart from the biological and instrumental points of view and adapts mathematical and statistical tools in order to analyze the data gathered. The biological motivation and current state of research is given as well as instrumental considerations and problems in the measurement of carbon dioxide production. A wide set of mathematical and statistical tools are used to analyze the time series produced in the laboratory. The objective is to assemble a methodology for the production and analysis of data that can be used in further developmental respiration research.


The Cleveland-Akron-Elyria Region Doing Well: More Persons Attending College And Getting Degrees, 2000 To 2007, Mark Salling Jan 2008

The Cleveland-Akron-Elyria Region Doing Well: More Persons Attending College And Getting Degrees, 2000 To 2007, Mark Salling

All Maxine Goodman Levin School of Urban Affairs Publications

Discussions of economic development and job availability in northeast Ohio often lament the unavailability of a qualified workforce in some sectors. Workforce training and attracting more educated population to the region are sited as important, even critical, objectives for the region. While a more detailed study of the regions’ workforce by The Center for Community Solutions is nearing completion, the release of new data by the Census Bureau provides some enlightening observations about college enrollments and educational attainment in the region.


Changes In Poverty And Educational Attainment, 2000 To 2007 Poverty Rates Increasing For Those With College Education, Too, Mark Salling Jan 2008

Changes In Poverty And Educational Attainment, 2000 To 2007 Poverty Rates Increasing For Those With College Education, Too, Mark Salling

All Maxine Goodman Levin School of Urban Affairs Publications

No abstract provided.


Hispanics And Asians Increase In Numbers In Cuyahoga County An Analysis Of 2007 County Population Estimates, Mark Salling Jan 2008

Hispanics And Asians Increase In Numbers In Cuyahoga County An Analysis Of 2007 County Population Estimates, Mark Salling

All Maxine Goodman Levin School of Urban Affairs Publications

No abstract provided.


Ohio Continues To Lag In Population Growth And Comments On Prospects For The Future An Analysis Of 2007 State Population Estimates, Mark Salling Jan 2008

Ohio Continues To Lag In Population Growth And Comments On Prospects For The Future An Analysis Of 2007 State Population Estimates, Mark Salling

All Maxine Goodman Levin School of Urban Affairs Publications

No abstract provided.