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Full-Text Articles in Physical Sciences and Mathematics

Learning About Modeling In Teacher Preparation Programs, Hyunyi Jung, Eryn Stehr, Jia He, Sharon L. Senk Dec 2017

Learning About Modeling In Teacher Preparation Programs, Hyunyi Jung, Eryn Stehr, Jia He, Sharon L. Senk

Hyunyi Jung

This study explores opportunities that secondary mathematics teacher preparation programs provide to learn about modeling in algebra. Forty-eight course instructors and ten focus groups at five universities were interviewed to answer questions related to modeling. With the analysis of the interview transcripts and related course materials, we found few opportunities for PSTs to engage with the full modeling cycle. Examples of opportunities to learn about algebraic modeling and the participants’ perspectives on the opportunities can contribute to the study of modeling and algebra in teacher education.


Teaching Statistics To Msw Students: Comparing Credit And Non-Credit Options, Ashley Davis, Rebecca G. Mirick Dec 2017

Teaching Statistics To Msw Students: Comparing Credit And Non-Credit Options, Ashley Davis, Rebecca G. Mirick

Rebecca Mirick

In professional disciplines like social work, students are expected to be able to understand and apply basic statistical concepts. Graduate programs differ in how they expect students to develop this ability; some require a full-credit statistics course as a prerequisite to admission, and others incorporate statistics into social work research courses. The for-credit requirement has a high financial and time cost for students. This exploratory study examined the feasibility of replacing this requirement with a brief, non-credit statistics course. MSW students (n=168) who took both types of courses were surveyed. No association was found between the type of course and …


Variational Bayes Estimation Of Discrete-Margined Copula Models With Application To Ime Series, Ruben Loaiza-Maya, Michael S. Smith Nov 2017

Variational Bayes Estimation Of Discrete-Margined Copula Models With Application To Ime Series, Ruben Loaiza-Maya, Michael S. Smith

Michael Stanley Smith

We propose a new variational Bayes estimator for high-dimensional copulas with discrete, or a combination of discrete and continuous, margins. The method is based on a variational approximation to a tractable augmented posterior, and is faster than previous likelihood-based approaches. We use it to estimate drawable vine copulas for univariate and multivariate Markov ordinal and mixed time series. These have dimension $rT$, where $T$ is the number of observations and $r$ is the number of series, and are difficult to estimate using previous methods. 
The vine pair-copulas are carefully selected to allow for heteroskedasticity, which is a feature of most ordinal …


Time Varying Parameter Estimation Scheme For A Linear Stochastic Differential Equation.Pdf, Michael Otunuga Aug 2017

Time Varying Parameter Estimation Scheme For A Linear Stochastic Differential Equation.Pdf, Michael Otunuga

Olusegun Michael Otunuga

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In this work, an attempt is made to estimate time varying parameters in a linear stochastic differential equation. By defining $m_{k}$ as the local admissible sample/data observation size at time $t_{k}$, parameters and state at time $t_{k}$ are estimated using past data on interval $[t_{k-m_{k}+1}, t_{k}]$. We show that the parameter estimates at each time $t_{k}$ converge in probability to the true value of the parameters being estimated. A numerical simulation is presented by applying the local lagged adapted generalized method of moments (LLGMM) method to the stochastic differential models governing prices …


Methods For Scalar-On-Function Regression, Philip T. Reiss, Jeff Goldsmith, Han Lin Shang, R. Todd Ogden Jul 2017

Methods For Scalar-On-Function Regression, Philip T. Reiss, Jeff Goldsmith, Han Lin Shang, R. Todd Ogden

Philip T. Reiss

Recent years have seen an explosion of activity in the field of functional data analysis (FDA), in which curves, spectra, images, etc. are considered as basic functional data units. A central problem in FDA is how to fit regression models with scalar responses and functional data points as predictors. We review some of the main approaches to this problem, categorizing the basic model types as linear, nonlinear and nonparametric. We discuss publicly available software packages, and illustrate some of the procedures by application to a functional magnetic resonance imaging dataset.


A Brief Review On Leading Big Data Models, Sugam Sharma, Udoyara S. Tim, Johnny S. Wong, Shashi Gadia, Subhash Sharma Jun 2017

A Brief Review On Leading Big Data Models, Sugam Sharma, Udoyara S. Tim, Johnny S. Wong, Shashi Gadia, Subhash Sharma

Sugam Sharma

Today, science is passing through an era of transformation, where the inundation of data, dubbed data deluge is influencing the decision making process. The science is driven by the data and is being termed as data science. In this internet age, the volume of the data has grown up to petabytes, and this large, complex, structured or unstructured, and heterogeneous data in the form of “Big Data” has gained significant attention. The rapid pace of data growth through various disparate sources, especially social media such as Facebook, has seriously challenged the data analytic capabilities of traditional relational databases. The velocity …


Contextual Motivation In Physical Activity By Means Of Association Rule Mining, Sugam Sharma, Udoyara Sunday Tim, Marinelle Payton, Hari Cohly, Shashi Gadia, Johnny Wong, Sudharshanam Karakala Jun 2017

Contextual Motivation In Physical Activity By Means Of Association Rule Mining, Sugam Sharma, Udoyara Sunday Tim, Marinelle Payton, Hari Cohly, Shashi Gadia, Johnny Wong, Sudharshanam Karakala

Sugam Sharma

The primary thrust of this work is to demonstrate the applicability of association rule mining in public health domain, focusing on physical activity and exercising. In this paper, the concept of association rule mining is shown assisting to promote the physical exercise as regular human activity. Specifically, similar to the prototypical example of association rule mining, market basket analysis, our proposed novel approach considers two events – exercise (sporadic) and sleep (regular) as the two items of the frequent set; and associating the former, exercise event, with latter, the daily occurring activity sleep at night, helps strengthening the frequency of …


Estimating Pay Gaps For Workers With Disabilities: Implications From Broadening Definitions And Data Sets, Kevin F. Hallock, Xin Jin, Linda Barrington Jun 2017

Estimating Pay Gaps For Workers With Disabilities: Implications From Broadening Definitions And Data Sets, Kevin F. Hallock, Xin Jin, Linda Barrington

Kevin F Hallock

Purpose: To compare pay gap estimates across 3 different national survey data sets for people with disabilities relative to those without disabilities when pay is measured as wage and salary alone versus a (total compensation) definition that includes an estimate of the value of benefits.

Method: Estimates of the cost to the employers of employee benefits at the occupational level from an employer survey data set are matched to individual-level data in each of the 3 data sets. Multiple regression techniques are applied to estimate wage and salary and total compensation gaps between full-time men with and without …


Discrimination By Gender And Disability Status: Do Worker Perceptions Match Statistical Measures?, Kevin F. Hallock, Wallace Hendricks, Emer Broadbent Jun 2017

Discrimination By Gender And Disability Status: Do Worker Perceptions Match Statistical Measures?, Kevin F. Hallock, Wallace Hendricks, Emer Broadbent

Kevin F Hallock

We explore whether perceptions of discrimination are related to ordinary statistical measures. The majority of disabled respondents report feeling some discrimination due to their disability, the majority of women feel some discrimination because of their gender, and a surprising number of men also report some discrimination. We do not find a strong link between perceptions of discrimination and measured discrimination perhaps because those who perceive discrimination feel that it occurs along other dimensions than pay. However, we do find a connection between whether a person feels his or her income is inadequate and measured discrimination for all groups studied.


A Brief Review On Leading Big Data Models, Sugam Sharma, Udoyara S. Tim, Johnny S. Wong, Shashi Gadia, Subhash Sharma Jun 2017

A Brief Review On Leading Big Data Models, Sugam Sharma, Udoyara S. Tim, Johnny S. Wong, Shashi Gadia, Subhash Sharma

Johnny Wong

Today, science is passing through an era of transformation, where the inundation of data, dubbed data deluge is influencing the decision making process. The science is driven by the data and is being termed as data science. In this internet age, the volume of the data has grown up to petabytes, and this large, complex, structured or unstructured, and heterogeneous data in the form of “Big Data” has gained significant attention. The rapid pace of data growth through various disparate sources, especially social media such as Facebook, has seriously challenged the data analytic capabilities of traditional relational databases. The velocity …


Contextual Motivation In Physical Activity By Means Of Association Rule Mining, Sugam Sharma, Udoyara Sunday Tim, Marinelle Payton, Hari Cohly, Shashi Gadia, Johnny Wong, Sudharshanam Karakala Jun 2017

Contextual Motivation In Physical Activity By Means Of Association Rule Mining, Sugam Sharma, Udoyara Sunday Tim, Marinelle Payton, Hari Cohly, Shashi Gadia, Johnny Wong, Sudharshanam Karakala

Johnny Wong

The primary thrust of this work is to demonstrate the applicability of association rule mining in public health domain, focusing on physical activity and exercising. In this paper, the concept of association rule mining is shown assisting to promote the physical exercise as regular human activity. Specifically, similar to the prototypical example of association rule mining, market basket analysis, our proposed novel approach considers two events – exercise (sporadic) and sleep (regular) as the two items of the frequent set; and associating the former, exercise event, with latter, the daily occurring activity sleep at night, helps strengthening the frequency of …


Prediction Of Remaining Life Of Power Transformers Based On Left Truncated And Right Censored Lifetime Data, Yili Hong, William Q. Meeker, James D. Mccalley Jun 2017

Prediction Of Remaining Life Of Power Transformers Based On Left Truncated And Right Censored Lifetime Data, Yili Hong, William Q. Meeker, James D. Mccalley

James McCalley

Prediction of the remaining life of high-voltage power transformers is an important issue for energy companies because of the need for planning maintenance and capital expenditures. Lifetime data for such transformers are complicated because transformer lifetimes can extend over many decades and transformer designs and manufacturing practices have evolved. We were asked to develop statistically-based predictions for the lifetimes of an energy company’s fleet of high-voltage transmission and distribution transformers. The company’s data records begin in 1980, providing information on installation and failure dates of transformers. Although the dataset contains many units that were installed before 1980, there is no …


Determining Graduation Rates In Engineering For Community College Transfer Students Using Data Mining, Marcia Laugerman, Diane T. Rover, Mack C. Shelley, Steven K. Mickelson Jun 2017

Determining Graduation Rates In Engineering For Community College Transfer Students Using Data Mining, Marcia Laugerman, Diane T. Rover, Mack C. Shelley, Steven K. Mickelson

Diane Rover

This study presents a unique synthesized set of data for community college students entering the university with the intention of earning a degree in engineering. Several cohorts of longitudinal data were combined with transcript-level data from both the community college and the university to measure graduation rates in engineering. The emphasis of the study is to determine academic variables that had significant correlations with graduation in engineering, and levels of these academic variables. The article also examines the utility of data mining methods for understanding the academic variables related to achievement in science, technology, engineering, and mathematics. The practical purpose …


The Engineering Admissions Partnership Program: A Navigation Strategy For Community College Students Seeking A Pathway Into Engineering, Marcia R. Laugerman, Mack C. Shelley, Steven K. Mickelson, Diane T. Rover Jun 2017

The Engineering Admissions Partnership Program: A Navigation Strategy For Community College Students Seeking A Pathway Into Engineering, Marcia R. Laugerman, Mack C. Shelley, Steven K. Mickelson, Diane T. Rover

Diane Rover

This paper presents the evaluation of a program designed to improve transfer outcomes for community college students pursuing an engineering degree. The program, the Engineering Admissions Partnership Program (E-APP), was designed to improve the navigational success of community college transfer students through connections to the university. These connections include coordinated academic advising, peer-mentoring, campus visits, and online social and professional networks. The objective of the study is to determine the efficacy of the E-APP and its interventions, which will be measured by increased participation rates and increased university retention rates for E-APP participants. Outcome data for the students are analyzed …


Propensity Score Analysis With Matching Weights, Liang Li Jun 2017

Propensity Score Analysis With Matching Weights, Liang Li

Liang Li

The propensity score analysis is one of the most widely used methods for studying the causal treatment effect in observational studies. This paper studies treatment effect estimation with the method of matching weights. This method resembles propensity score matching but offers a number of new features including efficient estimation, rigorous variance calculation, simple asymptotics, statistical tests of balance, clearly identified target population with optimal sampling property, and no need for choosing matching algorithm and caliper size. In addition, we propose the mirror histogram as a useful tool for graphically displaying balance. The method also shares some features of the inverse …


A Simple Method To Estimate The Time-Dependent Roc Curve Under Right Censoring, Liang Li, Bo Hu, Tom Greene Jun 2017

A Simple Method To Estimate The Time-Dependent Roc Curve Under Right Censoring, Liang Li, Bo Hu, Tom Greene

Liang Li

The time-dependent Receiver Operating Characteristic (ROC) curve is often used to study the diagnostic accuracy of a single continuous biomarker, measured at baseline, on the onset of a disease condition when the disease onset may occur at different times during the follow-up and hence may be right censored. Due to censoring, the true disease onset status prior to the pre-specified time horizon may be unknown on some patients, which causes difficulty in calculating the time-dependent sensitivity and specificity. We study a simple method that adjusts for censoring by weighting the censored data by the conditional probability of disease onset prior …


Vitamin D Status And Demographic And Lifestyle Determinants Among Adults In The United States (Nhanes 2001-2006), Yan Cao, Katie L. Callahan, Sreenivas P. Veeranki, Yang Chen, Ying Liu, Shimin Zheng May 2017

Vitamin D Status And Demographic And Lifestyle Determinants Among Adults In The United States (Nhanes 2001-2006), Yan Cao, Katie L. Callahan, Sreenivas P. Veeranki, Yang Chen, Ying Liu, Shimin Zheng

Shimin Zheng

This study looked at risk factors associated with vitamin D levels in the body among a representative sample of adults in the U.S., NHANES III (2001-2006) data were used to assess the relationship between several demographic and health risk factors and vitamin D levels in the body. The Baseline-Category Logit Model was used to test the association between vitamin D level and the potential risk factors age, education, ethnicity, poverty status, physical activity, smoking, alcohol, obesity, diabetes and total cholesterol with both genders. Vitamin D insufficiency and deficiency were significantly associated with age, race, education, physical activity, obesity, diabetes and …


Random Regression Models Based On The Elliptically Contoured Distribution Assumptions With Applications To Longitudinal Data, Alfred A. Bartolucci, Shimin Zheng, Sejong Bae, Karan P. Singh May 2017

Random Regression Models Based On The Elliptically Contoured Distribution Assumptions With Applications To Longitudinal Data, Alfred A. Bartolucci, Shimin Zheng, Sejong Bae, Karan P. Singh

Shimin Zheng

We generalize Lyles et al.’s (2000) random regression models for longitudinal data, accounting for both undetectable values and informative drop-outs in the distribution assumptions. Our models are constructed on the generalized multivariate theory which is based on the Elliptically Contoured Distribution (ECD). The estimation of the fixed parameters in the random regression models are invariant under the normal or the ECD assumptions. For the Human Immunodeficiency Virus Epidemiology Research Study data, ECD models fit the data better than classical normal models according to the Akaike (1974) Information Criterion. We also note that both univariate distributions of the random intercept and …


The Use Of Vital Statistics Data For Research Of Consequence: Birth Outcomes And Population Health In A Rural Region, Claudia Kozinetz, Shimin Zheng, Eunice Mogusu May 2017

The Use Of Vital Statistics Data For Research Of Consequence: Birth Outcomes And Population Health In A Rural Region, Claudia Kozinetz, Shimin Zheng, Eunice Mogusu

Shimin Zheng

Objective: The Affordable Care Act (ACA) has influenced increasing interests in population health and population health outcomes. The purpose of this study was to exemplify the importance of using existing vital statistics data for understanding and monitoring health outcomes and consequentially health disparities at the population level. Data from birth records for two geographic regions from 2009-2014 were compared; low birth weight (LBW) and preterm delivery (PD) were used as surrogates for population health outcomes. Methods: A population-based, multi-year, cross-sectional study design using a pooled dataset of birth records from Tennessee (TN) was the framework for the analyses. A sub-population …


Trends And Determinants Of Up-To-Date Status With Colorectal Cancer Screening In Tennessee, 2002-2008, Sreenivas P. Veeranki, Shimin Zheng May 2017

Trends And Determinants Of Up-To-Date Status With Colorectal Cancer Screening In Tennessee, 2002-2008, Sreenivas P. Veeranki, Shimin Zheng

Shimin Zheng

BACKGROUND: Screening rates for colorectal cancer (CRC) are increasing nationwide including Tennessee (TN); however, their up-to-date status is unknown. The objective of this study is to determine the trends and characteristics of TN adults who are up-to-date status with CRC screening during 2002-2008. METHODS: We examined data from the TN Behavioral Risk Factor Surveillance System for 2002, 2004, 2006 and 2008 to estimate the proportion of respondents aged 50 years and above who were up-to-date status with CRC screening, defined as an annual home fecal occult blood test and/or sigmoidoscopy or colonoscopy in the past 5 years. We identified trends …


The Association Of Calcium Intake And Other Risk Factors With Cardiovascular Disease Among Obese Adults In Usa, Yang Chen, Sheryl Strasser, Katie Callahan, David Blackley, Yan Cao, Liang Wang, Shimin Zheng May 2017

The Association Of Calcium Intake And Other Risk Factors With Cardiovascular Disease Among Obese Adults In Usa, Yang Chen, Sheryl Strasser, Katie Callahan, David Blackley, Yan Cao, Liang Wang, Shimin Zheng

Shimin Zheng

In this study, we used a cross-sectional study design to examine the relationship between the calcium intake and risk factors for CVD among obese adults by using continuous waves of National Health and Nutrition Examination Survey (NHANES) data 1999-2010. The association between calcium intake and risk factors of CVD (hypertension, total cholesterol, HDL, glycohemoglobin), CRP, albuminuria) is assessed among obese adults in USA. The incidence of Cardiovascular Disease (CVD) is high among obese people. The potential effects of inadequate calcium intake on CVD are receiving increased epidemiologic attention. Understanding the association between risk factors for CVD and calcium intake among …


Screening For Elder Mistreatment Among Older Adults Seeking Legal Assistance Services, Sheryl M. Strasser, Megan Smith, Scott Weaver, Shimin Zheng, Yan Cao May 2017

Screening For Elder Mistreatment Among Older Adults Seeking Legal Assistance Services, Sheryl M. Strasser, Megan Smith, Scott Weaver, Shimin Zheng, Yan Cao

Shimin Zheng

Introduction: The aging population is a rapidly growing demographic in the United States. Isolation, limited autonomy, and declining physical and mental health render many older adults vulnerable to elder mistreatment (EM). The purpose of this study was to assess the prevalence and correlates of EM among a sample of older adults using legal assistance services in Atlanta, Georgia. Methods: Researchers administered surveys to consenting older adults (aged 60þ) in 5 metro Atlanta community centers that hosted legal assistance information sessions as part of the Elderly Legal Assistance Program. The surveys screened for risk factors and prevalence of EM risk using …


Stochastic Representations Of The Matrix Variate Skew Elliptically Contoured Distributions, Shimin Zheng, Chunming Zhang, Jeff Knisley May 2017

Stochastic Representations Of The Matrix Variate Skew Elliptically Contoured Distributions, Shimin Zheng, Chunming Zhang, Jeff Knisley

Shimin Zheng

Matrix variate skew elliptically contoured distributions generalize several classes of important distributions. This paper defines and explores matrix variate skew elliptically contoured distributions. In particular, we discuss two stochastic representations of the matrix variate skew elliptically contoured distributions.


Predictors Of Neonatal Abstinence Syndrome In Buprenorphine Exposed Newborn: Can Cord Blood Buprenorphine Metabolite Levels Help?, Darshan Shah, Stacy Brown, Nick Hagemeier, Shimin Zheng, Amy Kyle, Jason Pryor, Nilesh Dankhara, Piyuesh Singh May 2017

Predictors Of Neonatal Abstinence Syndrome In Buprenorphine Exposed Newborn: Can Cord Blood Buprenorphine Metabolite Levels Help?, Darshan Shah, Stacy Brown, Nick Hagemeier, Shimin Zheng, Amy Kyle, Jason Pryor, Nilesh Dankhara, Piyuesh Singh

Shimin Zheng

Background

Buprenorphine is a semi-synthetic opioid used for the treatment of opioid dependence. Opioid use, including buprenorphine, has been increasing in recent years, in the general population and in pregnant women. Consequently, there has been a rise in frequency of neonatal abstinence syndrome (NAS), associated with buprenorphine use during pregnancy. The purpose of this study was to investigate correlations between buprenorphine and buprenorphine-metabolite concentrations in cord blood and onset of NAS in buprenorphine exposed newborns.

Methods

Nineteen (19) newborns who met inclusion criteria were followed after birth until discharge in a double-blind non-intervention study, after maternal consent. Cord blood and …


Prevalence Of And Risk Factors For Adolescent Obesity In Tennessee Using The 2010 Youth Risk Behavior Survey (Yrbs) Data: An Analysis Using Weighted Hierarchical Logistic Regression, Shimin Zheng, Nicole Holt, Jodi L. Southerland, Yan Cao, Trevor Taylor, Deborah L. Slawson, Mark Bloodworth May 2017

Prevalence Of And Risk Factors For Adolescent Obesity In Tennessee Using The 2010 Youth Risk Behavior Survey (Yrbs) Data: An Analysis Using Weighted Hierarchical Logistic Regression, Shimin Zheng, Nicole Holt, Jodi L. Southerland, Yan Cao, Trevor Taylor, Deborah L. Slawson, Mark Bloodworth

Shimin Zheng

Background: The rate of adolescent overweight and obesity has more than quadrupled over the past few decades, and has become a major public health problem [1]. In 2011, 55% of 12-19 year olds in the United States (U.S.) were overweight or obese [2]. Adolescence is a pivotal time in which many health risk behaviors such as tobacco, alcohol, and drug use are initiated. Such health risk behaviors have been significantly associated with overweight and obesity among adolescents. Objective: The purpose of this study is to evaluate the relationship between obesity and the health risk behaviors most commonly associated with premature …


Predictors Of Treatments Acceptable To Patients For Late-Life Depression, Gerald J. Jogerst, Shimin Zheng, Erik Vanderlip May 2017

Predictors Of Treatments Acceptable To Patients For Late-Life Depression, Gerald J. Jogerst, Shimin Zheng, Erik Vanderlip

Shimin Zheng

Objectives. Describe older patients’ perceptions about depression and characteristics associated with acceptance of treatments. Design. Cross-sectional study. Setting. Three primary care clinics in Iowa. Participants. Consecutive sample of 529 primary care patients. Measurements. Depression screening tool (a 9-item patient health questionnaire [PHQ-9]) and questionnaire including sociodemographic data, patient attitudes about depression, and acceptability of different treatments. Results. Mean age was 71.9 years (range 60–93 years), 314 (59%) female. Among the 529 participants, 93 (17.5%) had history of depression and 60 (11.3%) had PHQ-9 scores of 10 or greater. Participants believed depression is a disease for which they would use medication …


Moments Of Matrix Variate Skew Elliptically Contoured Distributions, Shimin Zheng, Jeff Knisley, Chunming Zhang May 2017

Moments Of Matrix Variate Skew Elliptically Contoured Distributions, Shimin Zheng, Jeff Knisley, Chunming Zhang

Shimin Zheng

Matrix variate skew elliptically contoured distributions generalize several classes of important distributions. This paper defines and explores matrix variate skew elliptically contoured distributions. In particular, we discuss the first two moments of the matrix variate skew elliptically contoured distributions.


Associations Of Smoking Status And Serious Psychological Distress With Chronic Obstructive Pulmonary Disease, Ke-Sheng Wang, Liang Wang, Shimin Zheng, Long-Yang Wu May 2017

Associations Of Smoking Status And Serious Psychological Distress With Chronic Obstructive Pulmonary Disease, Ke-Sheng Wang, Liang Wang, Shimin Zheng, Long-Yang Wu

Shimin Zheng

Background: Chronic obstructive pulmonary disease (COPD) has been a major public health problem due to its high prevalence, morbidity, and mortality. Smoking is a major risk factor for COPD, while serious psychological distress (SPD) is prevalent among COPD patients. However, no study focusing on the effect of SPD on COPD has been so far conducted, while few studies have focused on the associations of SPD and behavioral factors with COPD by smoking status. Objectives: This study aimed to examine the associations of SPD and behavioral factors (such as smoking and physical activity) with COPD. Materials and Methods: Weighted logistic regression …


Sidz Dc Article April Twenty, Sidney Twentythree Sr., Ann Test Apr 2017

Sidz Dc Article April Twenty, Sidney Twentythree Sr., Ann Test

Ann Test

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Implementing Propensity Score Matching With Network Data: The Effect Of Gatt On Bilateral Trade, Luca De Benedictis, Bruno Arpino, Alessandra Mattei Mar 2017

Implementing Propensity Score Matching With Network Data: The Effect Of Gatt On Bilateral Trade, Luca De Benedictis, Bruno Arpino, Alessandra Mattei

Luca De Benedictis

Motivated by the evaluation of the causal effect of the General Agreement on Tariffs and Trade on bilateral international trade flows, we investigate the role of network structure in propensity score matching under the assumption of strong ignorability. We study the sensitivity of causal inference with respect to the presence of characteristics of the network in the set of confounders conditional on which strong ignorability is assumed to hold. We find that estimates of the average causal effect are highly sensitive to the presence of node-level network statistics in the set of confounders. Therefore, we argue that estimates may suffer …