Matching Items (17)
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Including a covariate can increase power to detect an effect between two variables. Although previous research has studied power in mediation models, the extent to which the inclusion of a mediator will increase the power to detect a relation between two variables has not been investigated. The first study identified

Including a covariate can increase power to detect an effect between two variables. Although previous research has studied power in mediation models, the extent to which the inclusion of a mediator will increase the power to detect a relation between two variables has not been investigated. The first study identified situations where empirical and analytical power of two tests of significance for a single mediator model was greater than power of a bivariate significance test. Results from the first study indicated that including a mediator increased statistical power in small samples with large effects and in large samples with small effects. Next, a study was conducted to assess when power was greater for a significance test for a two mediator model as compared with power of a bivariate significance test. Results indicated that including two mediators increased power in small samples when both specific mediated effects were large and in large samples when both specific mediated effects were small. Implications of the results and directions for future research are then discussed.
ContributorsO'Rourke, Holly Patricia (Author) / Mackinnon, David P (Thesis advisor) / Enders, Craig K. (Committee member) / Millsap, Roger (Committee member) / Arizona State University (Publisher)
Created2013
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The present study examined the association of pain intensity and goal progress in a community sample of 132 adults with chronic pain who participated in a 21 day diary study. Multilevel modeling was employed to investigate the effect of morning pain intensity on evening goal progress as mediated by pain's

The present study examined the association of pain intensity and goal progress in a community sample of 132 adults with chronic pain who participated in a 21 day diary study. Multilevel modeling was employed to investigate the effect of morning pain intensity on evening goal progress as mediated by pain's interference with afternoon goal pursuit. Moderation effects of pain acceptance and pain catastrophizing on the associations between pain and interference with both work and lifestyle goal pursuit were also tested. The results showed that the relationship between morning pain and pain's interference with work goal pursuit in the afternoon was significantly moderated by a pain acceptance. In addition, it was found that the mediated effect differed across levels of pain acceptance; that is: (1) there was a significant mediation effect when pain acceptance was at its mean and one standard deviation below the mean; but (2) there was no mediation effect when pain acceptance was one standard deviation above the mean. It appears that high pain acceptance significantly attenuates the power of nociception in disrupting one's work goal pursuit. However, in the lifestyle goal model, none of the moderators were significant nor was there a significant association between pain interference with goal pursuit and goal progress. Only morning pain intensity significantly predicted afternoon interference with lifestyle goal pursuit. Further interpretation of the present findings and potential explanations of those inconsistencies are elaborated on discussion. Limitations and the clinical implication of the current study were considered, along with suggestions for future studies.
ContributorsMun, Chung Jung (Author) / Karoly, Paul (Thesis advisor) / Okun, Morris A. (Committee member) / Enders, Craig K. (Committee member) / Arizona State University (Publisher)
Created2014
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Research methods based on the frequentist philosophy use prior information in a priori power calculations and when determining the necessary sample size for the detection of an effect, but not in statistical analyses. Bayesian methods incorporate prior knowledge into the statistical analysis in the form of a prior distribution. When

Research methods based on the frequentist philosophy use prior information in a priori power calculations and when determining the necessary sample size for the detection of an effect, but not in statistical analyses. Bayesian methods incorporate prior knowledge into the statistical analysis in the form of a prior distribution. When prior information about a relationship is available, the estimates obtained could differ drastically depending on the choice of Bayesian or frequentist method. Study 1 in this project compared the performance of five methods for obtaining interval estimates of the mediated effect in terms of coverage, Type I error rate, empirical power, interval imbalance, and interval width at N = 20, 40, 60, 100 and 500. In Study 1, Bayesian methods with informative prior distributions performed almost identically to Bayesian methods with diffuse prior distributions, and had more power than normal theory confidence limits, lower Type I error rates than the percentile bootstrap, and coverage, interval width, and imbalance comparable to normal theory, percentile bootstrap, and the bias-corrected bootstrap confidence limits. Study 2 evaluated if a Bayesian method with true parameter values as prior information outperforms the other methods. The findings indicate that with true values of parameters as the prior information, Bayesian credibility intervals with informative prior distributions have more power, less imbalance, and narrower intervals than Bayesian credibility intervals with diffuse prior distributions, normal theory, percentile bootstrap, and bias-corrected bootstrap confidence limits. Study 3 examined how much power increases when increasing the precision of the prior distribution by a factor of ten for either the action or the conceptual path in mediation analysis. Power generally increases with increases in precision but there are many sample size and parameter value combinations where precision increases by a factor of 10 do not lead to substantial increases in power.
ContributorsMiocevic, Milica (Author) / Mackinnon, David P. (Thesis advisor) / Levy, Roy (Committee member) / West, Stephen G. (Committee member) / Enders, Craig (Committee member) / Arizona State University (Publisher)
Created2014
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I examined the role of children's or teacher's effortful control (EC) in children's academic functioning in early elementary school in two separate studies. In Study 1, I tested longitudinal relations between parents' reactions to children's displays of negative emotions in kindergarten, children's EC in first grade, and children's reading or

I examined the role of children's or teacher's effortful control (EC) in children's academic functioning in early elementary school in two separate studies. In Study 1, I tested longitudinal relations between parents' reactions to children's displays of negative emotions in kindergarten, children's EC in first grade, and children's reading or math achievement in second grade (N = 291). In the fall of each school year, parents reported their positive or negative reactions and parents and teachers reported on children's EC. Standardized achievement tests assessed achievement each spring. Results from autoregressive panel mediation models demonstrated that constructs exhibited consistency across study years. In addition, first-grade EC mediated relations between parents' reactions (i.e., a difference composite of positive minus negative reactions) at kindergarten and second-grade math, but not reading, achievement. Findings suggest that one method of promoting math achievement in early school is through the socialization of children's EC. In Study 2, I examined relations between teachers' EC, teachers' reactions to children's negative emotions, the student-teacher relationship (STR), and children's externalizing behaviors or achievement among 289 second-graders and their 116 teachers. Results from mixed-model regressions showed that negative reactions and teacher-reported STR mediated relations between teachers' EC and math achievement. In addition, teacher-reported STR mediated links between teachers' EC and externalizing problems across reporters and between teachers' EC and reading achievement. Tests of moderated mediation indicated that a high-quality STR was negatively associated with externalizing problems and high levels of teachers' negative reactions were negatively related to math achievement only for students low in EC. In tests of moderation by social competence, teachers' reports of high-quality STRs tended to be negatively associated with externalizing problems, but relations were strongest for students not high in social competence. For students low in social competence only, children's reports of a high-quality STR was related to lower reading achievement. These results highlight the utility of considering whether and how teachers' own intrinsic characteristics influence classroom dynamics and students' academic functioning outcomes.
ContributorsSwanson, Jodi Michelle (Author) / Valiente, Carlos (Thesis advisor) / Bradley, Robert H (Thesis advisor) / Kochenderfer-Ladd, Becky (Committee member) / Lemery-Chalfant, Kathryn (Committee member) / Arizona State University (Publisher)
Created2011
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Recent advances in hierarchical or multilevel statistical models and causal inference using the potential outcomes framework hold tremendous promise for mock and real jury research. These advances enable researchers to explore how individual jurors can exert a bottom-up effect on the jury’s verdict and how case-level features can exert a

Recent advances in hierarchical or multilevel statistical models and causal inference using the potential outcomes framework hold tremendous promise for mock and real jury research. These advances enable researchers to explore how individual jurors can exert a bottom-up effect on the jury’s verdict and how case-level features can exert a top-down effect on a juror’s perception of the parties at trial. This dissertation explains and then applies these technical advances to a pre-existing mock jury dataset to provide worked examples in an effort to spur the adoption of these techniques. In particular, the paper introduces two new cross-level mediated effects and then describes how to conduct ecological validity tests with these mediated effects. The first cross-level mediated effect, the a1b1 mediated effect, is the juror level mediated effect for a jury level manipulation. The second cross-level mediated effect, the a2bc mediated effect, is the unique contextual effect that being in a jury has on the individual the juror. When a mock jury study includes a deliberation versus non-deliberation manipulation, the a1b1 can be compared for the two conditions, enabling a general test of ecological validity. If deliberating in a group generally influences the individual, then the two indirect effects should be significantly different. The a2bc can also be interpreted as a specific test of how much changes in jury level means of this specific mediator effect juror level decision-making.
ContributorsLovis-McMahon, David (Author) / Schweitzer, Nicholas (Thesis advisor) / Saks, Michael (Thesis advisor) / Salerno, Jessica (Committee member) / MacKinnon, David (Committee member) / Arizona State University (Publisher)
Created2015
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Anxiety and depression are among the most prevalent disorders in youth, with prevalence rates ranging from 15% to 25% for anxiety and 5% to 14% for depression. Anxiety and depressive disorders cause significant impairment, fail to spontaneously remit, and have been prospectively linked to problematic substance use and legal problems

Anxiety and depression are among the most prevalent disorders in youth, with prevalence rates ranging from 15% to 25% for anxiety and 5% to 14% for depression. Anxiety and depressive disorders cause significant impairment, fail to spontaneously remit, and have been prospectively linked to problematic substance use and legal problems in adulthood. These disorders often share a high-degree of comorbidity in both clinical and community samples, with anxiety disorders typically preceding the onset of depression. Given the nature and consequences of anxiety and depressive disorders, a plethora of treatment and preventative interventions have been developed and tested with data showing significant pre to post to follow-up reductions in anxiety and depressive symptoms. However, little is known about the mediators by which these interventions achieve their effects. To address this gap in the literature, the present thesis study combined meta-analytic methods and path analysis to evaluate the effects of youth anxiety and depression interventions on outcomes and four theory-driven mediators using data from 55 randomized controlled trials (N = 11,413). The mediators included: (1) information-processing biases, (2) coping strategies, (3) social competence, and (4) physiological hyperarousal. Meta-analytic results showed that treatment and preventative interventions reliably produced moderate effect sizes on outcomes and three of the four mediators (information-processing biases, coping strategies, social competence). Most importantly, findings from the path analysis showed that changes in information-processing biases and coping strategies consistently mediated changes in outcomes for anxiety and depression at both levels of intervention, whereas gains in social competence and reductions in physiological hyperarousal did not emerge as significant mediators. Knowledge of the mediators underlying intervention effects is important because they can refine testable models of treatment and prevention efforts and identify which anxiety and depression components need to be packaged or strengthened to maximize intervention effects. Allocating additional resources to significant mediators has the potential to reduce costs associated with adopting and implementing evidence-based interventions and improve dissemination and sustainability in real-world settings, thus setting the stage to be more readily integrated into clinical and non-clinical settings on a large scale.
ContributorsStoll, Ryan (Author) / Pina, Armando A (Thesis advisor) / MacKinnon, David (Committee member) / Knight, George (Committee member) / Arizona State University (Publisher)
Created2015
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Mediation analysis is used to investigate how an independent variable, X, is related to an outcome variable, Y, through a mediator variable, M (MacKinnon, 2008). If X represents a randomized intervention it is difficult to make a cause and effect inference regarding indirect effects without making no unmeasured confounding assumptions

Mediation analysis is used to investigate how an independent variable, X, is related to an outcome variable, Y, through a mediator variable, M (MacKinnon, 2008). If X represents a randomized intervention it is difficult to make a cause and effect inference regarding indirect effects without making no unmeasured confounding assumptions using the potential outcomes framework (Holland, 1988; MacKinnon, 2008; Robins & Greenland, 1992; VanderWeele, 2015), using longitudinal data to determine the temporal order of M and Y (MacKinnon, 2008), or both. The goals of this dissertation were to (1) define all indirect and direct effects in a three-wave longitudinal mediation model using the causal mediation formula (Pearl, 2012), (2) analytically compare traditional estimators (ANCOVA, difference score, and residualized change score) to the potential outcomes-defined indirect effects, and (3) use a Monte Carlo simulation to compare the performance of regression and potential outcomes-based methods for estimating longitudinal indirect effects and apply the methods to an empirical dataset. The results of the causal mediation formula revealed the potential outcomes definitions of indirect effects are equivalent to the product of coefficient estimators in a three-wave longitudinal mediation model with linear and additive relations. It was demonstrated with analytical comparisons that the ANCOVA, difference score, and residualized change score models’ estimates of two time-specific indirect effects differ as a function of the respective mediator-outcome relations at each time point. The traditional model that performed the best in terms of the evaluation criteria in the Monte Carlo study was the ANCOVA model and the potential outcomes model that performed the best in terms of the evaluation criteria was sequential G-estimation. Implications and future directions are discussed.
ContributorsValente, Matthew J (Author) / Mackinnon, David P (Thesis advisor) / West, Stephen G. (Committee member) / Grimm, Keving (Committee member) / Chassin, Laurie (Committee member) / Arizona State University (Publisher)
Created2018
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A pressing question in public policymaking is how best to allocate decision-making authority and to facilitate opportunities for input. When it comes to science, technology, and environmental (STE) policy decisions, persons impacted by those decisions often have relevant information and perspectives to contribute yet lack either the specialized, technical knowledge

A pressing question in public policymaking is how best to allocate decision-making authority and to facilitate opportunities for input. When it comes to science, technology, and environmental (STE) policy decisions, persons impacted by those decisions often have relevant information and perspectives to contribute yet lack either the specialized, technical knowledge or the means by which to effectively communicate that knowledge. Consequently, due to a variety of factors, they are frequently denied meaningful involvement in making them. In an effort to better understand why this is so, and how this might change, this dissertation uses an activity systems framework to examine how three factors mediate the circulation of information in STE public engagement mechanisms.

In this project, I examine the transcripts of a 2015 administrative hearing and community meeting about the Santa Susana Field Lab—a former nuclear- and rocket engine-testing facility 30 miles from Los Angeles, where an experimental nuclear reactor suffered a partial meltdown in 1959. Specifically, I identify (1) who was designated as an "expert" versus a member of "the public," (2) the structural features, and (3) the stylistic features of participants' remarks at these events; and I study how these factors mediated the flow of information at each. To do so, I view "expert" and "public" as what Michael McGee has termed ideographs, and consider the structural and stylistic features that prior scholarship has identified to impact information flow.

Based on my analysis, I theorize that role designations, structural features, and stylistic features work together to mediate whose, what, and how information flows in public engagement mechanisms. Based on my findings, I also suggest that this mediation impacts policy outcomes. As such, I contend that better understanding the relationships among these mediational means, information flow, and policy outcomes is an important step towards developing public engagement mechanisms that most effectively use the relevant knowledge and other insights of all who have a stake in policy decisions.
ContributorsChurg, Emily (Author) / Long, Elenore (Thesis advisor) / Hannah, Mark (Thesis advisor) / Catlaw, Thomas (Committee member) / Arizona State University (Publisher)
Created2016
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Research on cultural socialization, the process in which individuals learn messages regarding the traditions and values of their culture (Hughes et al., 2006), has dedicated little attention to Latinx and Asian American groups. This study examined whether an interdependent self-construal (i.e., viewing oneself as connected to others and endorsing behaviors

Research on cultural socialization, the process in which individuals learn messages regarding the traditions and values of their culture (Hughes et al., 2006), has dedicated little attention to Latinx and Asian American groups. This study examined whether an interdependent self-construal (i.e., viewing oneself as connected to others and endorsing behaviors that depend on others; Singelis, 1994) was a mediator between cultural socialization and ethnic identity for these two groups. The current study utilized mediation analyses to explore the associations between cultural socialization via different agents (i.e., parents, teachers, romantic partners, peers), interdependent self-construal, and ethnic identity exploration and commitment for Latinx (N = 258, 68.6% female, Mage = 20.54) and Asian (N = 281, 66.5% female, Mage = 20.34) American college-attending emerging adults. Results revealed that for the Latinx sample, interdependent self-construal mediated the relation between cultural socialization and ethnic identity exploration or commitment in regards to parents and peers, but not teachers. In addition, interdependent self-construal mediated the association between cultural socialization from romantic partners and ethnic identity commitment, but not exploration. For the Asian American sample, interdependent self-construal mediated the association between cultural socialization and ethnic identity exploration or commitment in regards to romantic partners and peers, but not parents and teachers. These results highlight the important role of different cultural socialization agents in ethnic identity formation for these two groups and suggest that the endorsement of cultural values can be a mechanism through which ethnic identity is strengthened.
ContributorsLam, Christina (Author) / Tran, Alisia (Giac-Thao) (Thesis advisor) / Santos, Carlos (Committee member) / Yoo, Hyung Chol (Brandon) (Committee member) / Arizona State University (Publisher)
Created2017
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The Arizona Interfaith Alliance for Worker Justice (AIAWJ) was a mediating structure for those who wanted to be civically engaged in the labor movement and other coalitions in Phoenix, Arizona. It not only served its constituents, but it integrated, educated, and empowered them. Due to lack of funding the AIAWJ

The Arizona Interfaith Alliance for Worker Justice (AIAWJ) was a mediating structure for those who wanted to be civically engaged in the labor movement and other coalitions in Phoenix, Arizona. It not only served its constituents, but it integrated, educated, and empowered them. Due to lack of funding the AIAWJ closed in the summer of 2016. Many community members from marginalized neighborhoods, other concerned citizens, students, myself, and others participated in their first and only civic engagement opportunities through this organization and were subsequently left with no connections, a barrier to being civically engaged. Through interviews and secondary data research, the relationship between people, mediating structures, and civic engagement activity are examined. The key findings support existing research that emphasizes the importance of mediating structures when it comes to civic engagement.
ContributorsSickler, Shawn (Author) / Luna, Ilana (Thesis advisor) / Hager, Mark (Committee member) / Keahey, Jennifer (Committee member) / Arizona State University (Publisher)
Created2016