Yasemin Kisbu-Sakarya

Sweetened Drink and Snacking Cues in Adolescents: A Study Using Ecological Momentary Assessment

The objective of this study was to identify physical, social, and intrapersonal cues that were associated with the consumption of sweetened beverages and sweet and salty snacks among adolescents from lower SES neighborhoods. Students were recruited from high schools with a minimum level of 25% free or reduced cost lunches. Using ecological momentary assessment, participants (N=158) were trained to answer brief questionnaires on handheld PDA devices: (a) each time they ate or drank, (b) when prompted randomly, and (c) once each evening. Data were collected over 7days for each participant. Participants reported their location (e.g., school grounds, home), mood, social environment, activities (e.g., watching TV, texting), cravings, food cues (e.g., saw a snack), and food choices. Results showed that having unhealthy snacks or sweet drinks among adolescents was associated with being at school, being with friends, feeling lonely or bored, craving a drink or snack, and being exposed to food cues. Surprisingly, sweet drink consumption was associated with exercising. Watching TV was associated with consuming sweet snacks but not with salty snacks or sweet drinks. These findings identify important environmental and intrapersonal cues to poor snacking choices that may be applied to interventions designed to disrupt these food-related, cue-behavior linked habits.

Mechanisms of motivational interviewing in health promotion: a Bayesian mediation analysis

BackgroundCounselor behaviors that mediate the efficacy of motivational interviewing (MI) are not well understood, especially when applied to health behavior promotion. We hypothesized that client change talk mediates the relationship between counselor variables and subsequent client behavior change.MethodsPurposeful sampling identified individuals from a prospective randomized worksite trial using an MI intervention to promote firefighters’ healthy diet and regular exercise that increased dietary intake of fruits and vegetables (n = 21) or did not increase intake of fruits and vegetables (n = 22). MI interactions were coded using the Motivational Interviewing Skill Code (MISC 2.1) to categorize counselor and firefighter verbal utterances. Both Bayesian and frequentist mediation analyses were used to investigate whether client change talk mediated the relationship between counselor skills and behavior change.ResultsCounselors’ global spirit, empathy, and direction and MI-consistent behavioral counts (e.g., reflections, open questions, affirmations, emphasize control) significantly correlated with firefighters’ total client change talk utterances (rs = 0.42, 0.40, 0.30, and 0.61, respectively), which correlated significantly with their fruit and vegetable intake increase (r = 0.33). Both Bayesian and frequentist mediation analyses demonstrated that findings were consistent with hypotheses, such that total client change talk mediated the relationship between counselor’s skills—MI-consistent behaviors [Bayesian mediated effect: αβ = .06 (.03), 95% CI = .02, .12] and MI spirit [Bayesian mediated effect: αβ = .06 (.03), 95% CI = .01, .13]—and increased fruit and vegetable consumption.ConclusionMotivational interviewing is a resource- and time-intensive intervention, and is currently being applied in many arenas. Previous research has identified the importance of counselor behaviors and client change talk in the treatment of substance use disorders. Our results indicate that similar mechanisms may underlie the effects of MI for dietary change. These results inform MI training and application by identifying those processes critical for MI success in health promotion domains.

Inhibitory control effects in adolescent binge eating and consumption of sugar-sweetened beverages and snacks.

Inhibitory control and sensitivity to reward are relevant to the food choices individuals make frequently. An imbalance of these systems can lead to deficits in decision-making that are relevant to food ingestion. This study evaluated the relationship between dietary behaviors - binge eating and consumption of sweetened beverages and snacks - and behavioral control processes among 198 adolescents, ages 14 to 17. Neurocognitive control processes were assessed with the Iowa Gambling Task (IGT), a generic Go/No-Go task, and a food-specific Go/No-Go task. The food-specific version directly ties the task to food cues that trigger responses, addressing an integral link between cue-habit processes. Diet was assessed with self-administered food frequency and binge eating questionnaires. Latent variable models revealed marked gender differences. Inhibitory problems on the food-specific and generic Go/No-Go tasks were significantly correlated with binge eating only in females, whereas inhibitory problems measured with these tasks were the strongest correlates of sweet snack consumption in males. Higher BMI percentile and sedentary behavior also predicted binge eating in females and sweet snack consumption in males. Inhibitory problems on the generic Go/No-Go, poorer affective decision-making on the IGT, and sedentary behavior were associated with sweetened beverage consumption in males, but not females. The food-specific Go/No-Go was not predictive in models evaluating sweetened beverage consumption, providing some initial discriminant validity for the task, which consisted of sweet/fatty snacks as no-go signals and no sugar-sweetened beverage signals. This work extends research findings, revealing gender differences in inhibitory function relevant to behavioral control. Further, the findings contribute to research implicating the relevance of cues in habitual behaviors and their relationship to snack food consumption in an understudied population of diverse adolescents not receiving treatment for eating disorders.

Sensitivity Plots for Confounder Bias in the Single Mediator Model

Background: Causal inference continues to be a critical aspect of evaluation research. Recent research in causal inference for statistical mediation has focused on addressing the sequential ignorability assumption; specifically, that there is no confounding between the mediator and the outcome variable. Objectives: This article compares and contrasts three different methods for assessing sensitivity to confounding and describes the graphical depiction of these methods. Design: Two types of data were used to fully examine the plots for sensitivity analysis. The first type was generated data from a single mediator model with a confounder influencing both the mediator and the outcome variable. The second was data from an actual intervention study. With both types of data, situations are examined where confounding has a large effect and a small effect. Subjects: The nonsimulated data were from a large intervention study to decrease intentions to use steroids among high school football players. We demonstrate one situation where confounding is likely and another situation where confounding is unlikely. Conclusions: We discuss how these methods could be implemented in future mediation studies as well as the limitations and future directions for these methods.

A Monte Carlo Comparison Study of the Power of the Analysis of Covariance, Simple Difference, and Residual Change Scores in Testing Two-Wave Data:

This study compares the analysis of covariance (ANCOVA), difference score, and residual change score methods in testing the group effect for pretest–posttest data in terms of statistical power and Type I error rates using a Monte Carlo simulation. Previous research has mathematically shown the effect of stability of individual scores from pretest to posttest, reliability, and nonrandomization (i.e., pretest imbalance) on the performance of the ANCOVA, difference score, and residual change score methods. However, related power issues have not been adequately addressed. The authors examined the impact of stability of measurement over time, reliability of covariate and criterion, nonrandomization, sample size, and treatment effect size on statistical power of the three methods. Across conditions, ANCOVA and residual change score methods had similar power rates. When reliability was less than perfect, ANCOVA had more power than the difference score method when there was an increase from pretest to posttest and a positive baseline imbalance (i.e., treatment group had higher pretest scores than the control group), or when there was a decrease from pretest to posttest and a negative baseline imbalance, and vice versa. In case of perfect reliability, the statistical power of ANCOVA did not differ from the difference score method. For the difference score method, when reliability was low, there was no effect of stability on power, whereas when reliability was high or perfect, power increased as stability increased for medium and large effect sizes. Difference scores may be preferred over ANCOVA under certain circumstances.

The Distribution of the Product Explains Normal Theory Mediation Confidence Interval Estimation

The distribution of the product has several useful applications. One of these applications is its use to form confidence intervals for the indirect effect as the product of 2 regression coefficients. The purpose of this article is to investigate how the moments of the distribution of the product explain normal theory mediation confidence interval coverage and imbalance. Values of the critical ratio for each random variable are used to demonstrate how the moments of the distribution of the product change across values of the critical ratio observed in research studies. Results of the simulation study showed that as skewness in absolute value increases, coverage decreases. And as skewness in absolute value and kurtosis increases, imbalance increases. The difference between testing the significance of the indirect effect using the normal theory versus the asymmetric distribution of the product is further illustrated with a real data example. This article is the first study to show the direct link between the distribution of the product and indirect effect confidence intervals and clarifies the results of previous simulation studies by showing why normal theory confidence intervals for indirect effects are often less accurate than those obtained from the asymmetric distribution of the product or from resampling methods.

Worksite wellness program implementation: a model of translational effectiveness

ABSTRACTOccupational health promotion programs with documented efficacy have not penetrated worksites. Establishing an implementation model would allow focusing on mediating aspects to enhance installation and use of evidence-based occupational wellness interventions. The purpose of the study was to implement an established wellness program in fire departments and define predictors of program exposure/dose to outcomes to define a cross-sectional model of translational effectiveness. The study is a prospective observational study among 12 NW fire departments. Data were collected before and following installation, and findings were used to conduct mediation analysis and develop a translational effectiveness model. Worker age was examined for its impact. Leadership, scheduling/competing demands, and tailoring were confirmed as model components, while organizational climate was not a factor. The established model fit data well (χ2(9) = 25.57, CFI = 0.99, RMSEA = 0.05, SRMR = 0.03). Older firefighters, nearing retirement, appeared to have influences that both enhanced and hindered participation. Findings can inform implementation of worksite wellness in fire departments, and the prioritized influences and translational model can be validated and manipulated in these and other settings to more efficiently move health promotion science to service.

Bias, Type I Error Rates, and Statistical Power of a Latent Mediation Model in the Presence of Violations of Invariance:

When testing a statistical mediation model, it is assumed that factorial measurement invariance holds for the mediating construct across levels of the independent variable X. The consequences of failing to address the violations of measurement invariance in mediation models are largely unknown. The purpose of the present study was to systematically examine the impact of mediator noninvariance on the Type I error rates, statistical power, and relative bias in parameter estimates of the mediated effect in the single mediator model. The results of a large simulation study indicated that, in general, the mediated effect was robust to violations of invariance in loadings. In contrast, most conditions with violations of intercept invariance exhibited severely positively biased mediated effects, Type I error rates above acceptable levels, and statistical power larger than in the invariant conditions. The implications of these results are discussed and recommendations are offered.