Donna L Coffman

• Pennsylvania State University

Background Causal mediation analysis plays a crucial role in examining causal effects and causal mechanisms. Yet, limited work has taken into consideration the use of sampling weights in causal mediation analysis. In this study, we compared different strategies of incorporating sampling weights into causal mediation analysis. Methods We conducted...

Mediation analysis is a statistical approach that can provide insights regarding the intermediary processes by which an intervention or exposure affects a given outcome. Mediation analyses rose to prominence, particularly in social science research, with the publication of Baron and Kenny’s seminal paper and is now commonly applied in many research...

Prior work in causal inference has shown that using survey sampling weights in the propensity score estimation stage and the outcome model stage for binary treatments can result in a more robust estimator of the effect of the binary treatment being analyzed. However, to date, extending this work to continuous treatments and exposures has not been e...

Objective To provide step-by-step guidance and STATA and R code for using propensity score (PS) weighting to estimate moderation effects with categorical variables. Research design Tutorial illustrating the key steps for estimating and testing moderation using observational data. Steps include (1) examining covariate overlap across treatment group...

Background: Prominent theories suggest that individuals with co-occurring traumatic stress symptoms (TSS) and substance use (SU) may be less responsive to SU treatment compared to those with SU only. However, empirical findings in adult samples are mixed, and there has been limited work among adolescents. This study assesses the association between...

The increase in the use of mobile and wearable devices now allows dense assessment of mediating processes over time. For example, a pharmacological intervention may have an effect on smoking cessation via reductions in momentary withdrawal symptoms. We define and identify the causal direct and indirect effects in terms of potential outcomes on the...

Background Traditional mediation analysis typically examines the relations among an intervention, a time-invariant mediator, and a time-invariant outcome variable. Although there may be a total effect of the intervention on the outcome, there is a need to understand the process by which the intervention affects the outcome (i.e., the indirect effec...

Objective. To provide step-by-step guidance and STATA and R code for using propensity score (PS) weighted analyses when estimating moderation effects. Data Sources and Study Setting. Using data on 41,832 adults from the 2019 National Survey on Drug Use and Health (NSDUH), we examine if gender moderates the association between sexual minority status...

Introduction: The addictive nature of nicotine makes smoking cessation an extremely challenging process. With prolonged exposure, tobacco smoking transforms from being a positive reinforcer to a negative one, as smoking is used to mitigate aversive withdrawal symptoms. Studying the variations in withdrawal symptoms, especially during their peak in...

The increase in the use of mobile and wearable devices now allow dense assessment of mediating processes over time. For example, a pharmacological intervention may have an effect on smoking cessation via reductions in momentary withdrawal symptoms. We define and identify the causal direct and indirect effects in terms of potential outcomes on the m...

This paper is concerned with causal mediation analysis with varying indirect and direct effects. We propose a varying coefficient mediation model, which can also be viewed as an extension of moderation analysis on a causal diagram. We develop a new estimation procedure for the direct and indirect effects based on B-splines. Under mild conditions, r...

Weighted estimators are commonly used for estimating exposure effects in observational settings to establish causal relations. These estimators have a long history of development when the exposure of interest is binary and where the weights are typically functions of an estimated propensity score. Recent developments in optimization-based estimator...

Background: Traditional mediation analysis typically examines the relations among an intervention, a time-invariant mediator, and a time-invariant outcome variable. Although there may be a total effect of the intervention on the outcome, there is a need to understand the process by which the intervention affects the outcome (i.e. the indirect effec...

The current study seeks to advance understanding about how to address substance use and co-occurring mental health problems in adolescents. Specifically, we compared the effectiveness of two evidence-based treatment programs (Motivational Enhancement Treatment/Cognitive Behavior Therapy, 5 Sessions [MET/CBT5] and Adolescent Community Reinforcement...

Background: Causal effect estimation with observational data is subject to bias due to confounding, which is often controlled for using propensity scores. One unresolved issue in propensity score estimation is how to handle missing values in covariates. Method: Several approaches have been proposed for handling covariate missingness, including m...

Information criteria (ICs) based on penalized likelihood, such as Akaike's information criterion (AIC), the Bayesian information criterion (BIC) and sample-size-adjusted versions of them, are widely used for model selection in health and biological research. However, different criteria sometimes support different models, leading to discussions abou...

BACKGROUND Ambulatory assessment of electrodermal activity (EDA) is an emerging technique for capturing individuals’ autonomic responses to real-life events. There is currently little guidance available for processing and analyzing such data in the ambulatory setting. OBJECTIVE The primary goal of this manuscript is to describe and implement sever...

Background Ambulatory assessment of electrodermal activity (EDA) is an emerging technique for capturing individuals’ autonomic responses to real-life events. There is currently little guidance available for processing and analyzing such data in an ambulatory setting. Objective This study aimed to describe and implement several methods for preproce...

Researchers are sometimes interested in predicting a distal or external outcome (such as smoking cessation at follow-up) from the trajectory of an intensively recorded longitudinal variable (such as urge to smoke). This can be done in a semiparametric way via scalar-on-function regression. However, the resulting fitted coefficient regression functi...

Information criteria (ICs) based on penalized likelihood, such as Akaike's Information Criterion (AIC), the Bayesian Information Criterion (BIC), and sample-size-adjusted versions of them, are widely used for model selection in health and biological research. However, different criteria sometimes support different models, leading to discussions abo...

Choosing a model with too few parameters can involve making unrealistically simple assumptions and lead to high bias, poor prediction, and missed opportunities for insight. Such models are not flexible enough to describe the sample or the population well. A model with too many parameters can fit the observed data very well, but be too closely tailo...

This study used propensity scores to statistically approximate the causal effect of having aggressive friends on aggressive behavior in childhood. Participants were 1355 children (53 percent girls; 31 percent minority) in 97 third and fifth grade classrooms enrolled in the Classroom Peer Ecologies Project. Propensity scores were calculated to contr...

Although early sexual initiation has been linked to negative outcomes, it is unknown whether these effects are causal. In this study, we use propensity score methods to estimate the causal effect of early sexual initiation on young adult sexual risk behaviors and health outcomes using data from the National Longitudinal Study of Adolescent to Adult...

Choosing a model with too few parameters can involve making unrealistically simple assumptions and lead to high bias, poor prediction, and missed opportunities for insight. Such models are not flexible enough to describe the sample or the population well. A model with too many parameters can fit the observed data very well, but be too closely tailo...

Choosing a model with too few parameters can involve making unrealistically simple assumptions and lead to high bias, poor prediction, and missed opportunities for insight. Such models are not flexible enough to describe the sample or the population well. A model with too many parameters can t the observed data very well, but be too closely tailore...

Choosing a model with too few parameters can involve making unrealistically simple assumptions and lead to high bias, poor prediction, and missed opportunities for insight. Such models are not flexible enough to describe the sample or the population well. A model with too many parameters can fit the observed data very well, but be too closely tailo...

Background: Breast density is an established predictor of breast cancer risk, and there is considerable interest in associations of modifiable lifestyle factors, such as diet, with breast density. Objective: To determine whether dietary energy density (ED) is associated with percent dense breast volume (%DBV) and absolute dense breast volume (AD...

Peer relationships are one of the most proximal developmental contexts for youth, yet causal inferences regarding peer influence are often weak due to the confounding of peer selection (i.e., processes through which individuals choose to interact with other youth) and peer socialization (i.e., process through which an individual’s behavior is shape...

Health care resource consumption is a growing concern. The aim of this study was to examine the associations between diet quality and body mass index with health care resource use (HRU) in a cohort of advanced age. Participants in the Geisinger Rural Aging Study (n=5,993) were mailed demographic and dietary questionnaires in 2009. Of those eligible...

In an aging population, potentially modifiable factors impacting mortality such as diet quality, body mass index (BMI), and health-related quality of life (HRQOL) are of interest. Surviving members of the Geisinger Rural Aging Study (GRAS) (n = 5,993; aged ?74 years) were contacted in the fall of 2009. Participants in the present study were the 2,9...

Objectives To determine the associations between diet quality, body mass index (BMI), and health-related quality of life (HRQOL) as assessed by the health and activity limitation index (HALex) in older adults. Design Multivariate linear regression models were used to analyze associations between Dietary Screening Tool (DST) scores, BMI and HALex sc...

Prevention scientists use latent class analysis (LCA) with increasing frequency to characterize complex behavior patterns and profiles of risk. Often, the most important research questions in these studies involve establishing characteristics that predict membership in the latent classes, thus describing the composition of the subgroups and suggest...

To assess the association of diet-related practices and BMI with diet quality in rural adults aged ≥74 years. Cross-sectional. Dietary quality was assessed by the twenty-five-item Dietary Screening Tool (DST). Diet-related practices were self-reported. Multivariate linear regression models were used to analyse associations of DST scores with BMI an...

The integration of modern methods for causal inference with latent class analysis (LCA) allows social, behavioral, and health researchers to address important questions about the determinants of latent class membership. In the present article, two propensity score techniques, matching and inverse propensity weighting, are demonstrated for conductin...

Background: The prevalence of obesity-related adverse health outcomes is increasing among older adults. Because it is thought that nutrition plays an important role in successful aging, there has been considerable interest in the association between dietary patterns of older adults and obesity-related health outcomes. Objective: This study exami...

Introduction: The association between depression and sexual risk behaviors and sexually transmitted infections (STIs) has been well-established in the literature. While the temporal sequencing of the events provides evidence of which comes first, inferring causation remains difficult as other variables might explain the association. Causal inferenc...

Introduction. The Surgeon General recently reinforced the importance of preventing youth tobacco use with a report detailing the scope, negative consequences, and risk factors for use (US DHHS, 2012). Smoking behavior is multifaceted and understanding how to prevent it requires consideration of individual behavior in concert with availability and p...

Introduction. Substance use, abuse, and dependence are known to be associated with elevated levels of depression (e.g., Brook, et al., 2002), yet it is unclear whether substance use behavior profiles have a long-term causal impact on depression. Recent advances in causal inference methods have been proposed to account for possible confounders (i.e....

Life events such as marriage and stable employment have been found to facilitate the desistence of antisocial behavior during the transition from adolescence to young adulthood (Laub & Sampson, 1993; Le Blanc & Loeber, 1998), whereas alcohol use has been identified as a risk factor during this process, the effect of which is moderated by gender (Hu...

Weight change is a common health concern among the elderly, yet little is known about the relationship between weight change and dietary patterns (DP) in older adults, especially the very old (≥ 75 y). This investigation examined the association between DP and 5‐ year weight change in community‐dwelling older adults (n=270; mean ± SD age: 78.6±3.9...

Nutrition status is a predictor of quality of life. This study sought to determine the association between diet quality, BMI, and health‐related quality of life (HRQOL) in a population of adults ≥74 y. The Diet Screening Tool (DST) is a 25 item questionnaire scored from 0 (poor) to 100 developed to assess diet quality in older adults. The Health an...

Dietary pattern (DP) analyses have been successfully used to study the effects of total diet on health outcomes. This cross‐sectional study used latent class analysis to derive DPs in a cohort of 250 young adult women (25–29y) originally enrolled between 8–10y into the Dietary Intervention Study in Children. Using repeated 24‐ hour dietary recall d...

Objectives: To characterize dietary patterns among a diverse sample of older adults (≥ 65 years). Design: Cross-sectional. Setting: Five counties in west central Alabama. Participants: Community-dwelling Medicare beneficiaries (N=416; 76.8 ± 5.2 years, 56% female, 39% African American) in the University of Alabama at Birmingham (UAB) Study o...

Assessing mediation is important because most interventions are designed to affect an intermediate variable or mediator; this mediator, in turn, is hypothesized to affect outcome behaviors. Although there may be randomization to the intervention, randomization to levels of the mediator is not generally possible. Therefore, drawing causal inferences...

Researchers often hypothesize that a causal variable, whether randomly assigned or not, has an effect on an outcome behavior and that this effect may vary across levels of initial risk of engaging in the outcome behavior. In this paper, we propose a method for quantifying initial risk status. We then illustrate the use of this risk-status variable...

Mediation is usually assessed by a regression-based or structural equation modeling (SEM) approach that we will refer to as the classical approach. This approach relies on the assumption that there are no confounders that influence both the mediator, M, and the outcome, Y. This assumption holds if individuals are randomly assigned to levels of M bu...

Using seven waves of data, collected twice a year from the 8th through the 11th grades in a low-resource community in Cape Town, South Africa, we aimed to describe the developmental trends in three specific leisure experiences (leisure boredom, new leisure interests, and healthy leisure) and substance use (cigarettes, alcohol, and marijuana) behavi...

The relationship between food intake patterns and obesity remains unclear. The objective of the present review was to evaluate the current body of literature on food intake patterns of older adults and their associations with weight status, including obesity and waist circumference. Eleven observational studies were identified and reviewed. Diets c...

The present study examines the impact of the HealthWise South Africa prevention intervention on condom use self-efficacy. Students from the Cape Town area were assessed at the beginning and end of each school year, beginning in the 8th grade and ending in the 11th. The intervention was delivered in 12 lessons during the 8th grade and 6 lessons duri...

We show how to test hypotheses for coefficient alpha in three different situations: (1) hypothesis tests of whether coefficient alpha equals a prespecified value, (2) hypothesis tests involving two statistically independent sample alphas as may arise when testing the equality of coefficient alpha across groups, and (3) hypothesis tests involving tw...

Nutrient comparisons were made among subsets of older adults participating in the Geisinger Rural Aging Study (GRAS) (n=253) and the University of Alabama at Birmingham (UAB) Study of Aging (n=333) (mean age: GRAS=78.5 years, ± 3.8; UAB=72.4, ±5.21). The GRAS cohort is mainly Caucasian and rural. In contrast, the UAB cohort is 40% African American...

The sense of community index (SCI) has been widely used to measure psychological sense of community (SOC). Furthermore, SOC has been found to differ among racial groups. Since different ethnic groups have different cultural and historical experiences that may lead to different interpretations of measurement items, it is important to know whether th...

Confidence intervals for the intraclass correlation coefficient (ICC) have been proposed under the assumption of multivariate normality. We propose confidence intervals which do not require distributional assumptions. We performed a simulation study to assess the coverage rates of normal theory (NT) and asymptotically distribution free (ADF) interv...

The present study investigated the degree to which violation of the parameter drift assumption affects the Type I error rate for the test of close fit and power analysis procedures proposed by MacCallum, Browne, and Sugawara (1996) for both the test of close fit and the test of exact fit. The parameter drift assumption states that as sample size in...

The transition from high school to college provides a potentially critical window to intervene and reduce risky behavior among adolescents. Understanding the motivations (e.g., social, coping, enhancement) behind high school seniors' alcohol use could provide one important avenue to reducing risky drinking behaviors. In the present study, latent cl...

Reports an error in "Asymptotically distribution-free (ADF) interval estimation of coefficient alpha" by Alberto Maydeu-Olivares, Donna L. Coffman and Wolfgang M. Hartmann ( Psychological Methods , 2007[Jun], Vol 12[2], 157-176). The sentence describing Equation 1 is incorrect. The corrected sentence is presented in the erratum. (The following abst...

The point estimate of sample coefficient alpha may provide a misleading impression of the reliability of the test score. Because sample coefficient alpha is consistently biased downward, it is more likely to yield a misleading impression of poor reliability. The magnitude of the bias is greatest precisely when the variability of sample alpha is gre...

The common factor model assumes that the linear coefficients (intercepts and factor loadings) linking the observed variables to the latent factors are fixed coefficients (i.e., common for all participants). When the observed variables are participants' observed responses to stimuli, such as their responses to the items of a questionnaire, the assum...

Bartholomew and Leung proposed a limited-information goodness-of-fit test statistic (Y) for models fitted to sparse 2(P ) contingency tables. The null distribution of Y was approximated using a chi-squared distribution by matching moments. The moments were derived under the assumption that the model parameters were known in advance and it was conje...

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2005. Includes bibliographical references (leaves 140-144). Microfiche. s