Browsing by Subject "Meta-analysis"
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Item Data Related to Association studies of up to 1.2 million individuals yield new insights into the genetic etiology of tobacco and alcohol use(2019-01-16) Liu, Mengzhen; Jiang, Yu; Wedow, Robbee; Li, Yue; Brazel, David M; Chen, Fang; Datta, Gargi; Davila-Velderrain, Jose; McGuire, Daniel; Tian, Chao; Zhan, Xiaowei; 23andMe Research Team; HUNT All-In Psychiatry; Choquet, Hélène; Docherty, Anna R; Faul, Jessica D; Foerster, Johanna R; Fritsche, Lars G; Gabrielsen, Maiken Elvestad; Gordon, Scott D; Haessler, Jeffrey; Hottenga, Jouke-Jan; Huang, Hongyan; Jang, Seon-Kyeong; Jansen, Philip R; Ling, Yueh; Mägi, Reedik; Matoba, Nana; McMahon, George; Mulas, Antonella; Orrù, Valeria; Palviainen, Teemu; Pandit, Anita; Reginsson, Gunnar W, Skogholt, Anne Heidi; Smith, Jennifer A; Taylor, Amy E; Turman, Constance; Willemsen, Gonneke; Young, Hannah; Young, Kendra A; Zajac, Gregory J M; Zhao, Wei; Zhou, Wei; Bjornsdottir, Gyda; Boardman, Jason D; Boehnke, Michael; Boomsma, Dorret I; Chen, Chu; Cucca, Francesco; Davies, Gareth E; Eaton, Charles B; Ehringer, Marissa A; Esko, Tõnu; Fiorillo, Edoardo; Gillespie, Nathan A; Gudbjartsson, Daniel F; Haller, Toomas; Harris, Kathleen Mullan; Heath, Andrew C; Hewitt, John K; Hickie, Ian B; Hokanson, John E; Hopfer, Christian J; Hunter, David J; Iacono, William G; Johnson, Eric O; Kamatani, Yoichiro; Kardia, Sharon L. R; Keller, Matthew C; Kellis, Manolis; Kooperberg, Charles; Kraft, Peter; Krauter, Kenneth S; Laakso, Markku; Lind, Penelope A; Loukola, Anu; Lutz, Sharon M; Madden, Pamela A F; Martin, Nicholas G; McGue, Matt; McQueen, Matthew B; Medland, Sarah E; Metspalu, Andres; Mohlke, Karen L; Nielsen, Jonas B; Okada, Yukinori; Peters, Ulrike; Polderman, Tinca J C; Posthuma, Danielle; Reiner, Alexander P; Rice, John P; Rimm, Eric; Rose, Richard J; Runarsdottir, Valgerdur; Stallings, Michael C; Stančáková, Alena; Stefansson, Hreinn; Thai, Khanh K; Tindle, Hilary A; Tyrfingsson, Thorarinn; Wall, Tamara L; Weir, David R; Weisner, Constance; Whitfield, John B; Winsvold, Bendik Slagsvold; Yin, Jie; Zuccolo, Luisa; Bierut, Laura J; Hveem, Kristian; Lee, James J; Munafò, Marcus R; Saccone, Nancy L; Willer, Cristen J; Cornelis, Marilyn C; David, Sean P; Hinds, David A; Jorgenson, Eric; Kaprio, Jaakko; Stitzel, Jerry A; Stefansson, Kari; Thorgeirsson, Thorgeir E; Abecasis, Gonçalo; Liu Dajiang J; Vrieze Scott; liu00282@umn.edu; Liu, MengzhenWe conducted a meta-analysis of over 30 genome wide association studies (GWAS) in over 1.2 million participants with European ancestry on nicotine and substance use. Specifically, we targeted different stages and kinds of substance use from initiation (smoking initiation and age of regular smoking initiation) to regular use (drinks per week and cigarettes per day) to cessation (smoking cessation). The GWAS included have all been imputed to Haplotype Reference Consortium, 1000 Genomes or a combination including more specific reference panels. The studies are then meta-analyzed using sample size, allele frequencies and the imputation quality score as weight. Here we present the final set of filtered meta-analysis summary statistics as presented in the paper (https://doi.org/10.1038/s41588-018-0307-5) excluding 23andMe. As per requirement and to ease dissemination of our results for other scientific endeavors, we are sharing our results here to facilitate downloading.Item Data Related to Meta-analysis of up to 622,409 individuals identifies 40 novel smoking behaviour associated genetic loci(2019-02-04) GSCAN; Consortium for Genetics of Smoking Behaviour; CHD Exome+ consortium; erzurumlumesut@gmail.com; Erzurumluoglu, A. Mesut; Consortium for Genetics of Smoking Behaviour; GSCAN consortium; CHDExome+ consortiumSmoking is a major heritable and modifiable risk factor for many diseases, including cancer, common respiratory disorders and cardiovascular diseases. We tested up to 235,116 single nucleotide variants (SNVs) on the exome-array for association with smoking initiation, cigarettes per day, pack-years, and smoking cessation in a fixed effects meta-analysis of up to 61 studies (up to 346,813 participants). SNV-trait associations with P < 5 × 10−8 in either analysis were taken forward for replication in up to 275,596 independent participants from UK Biobank. Lastly, a meta-analysis of the discovery and replication studies was performed. These novel loci will facilitate understanding the genetic aetiology of smoking behaviour and may lead to the identification of potential drug targets for smoking prevention and/or cessation.Item An empirical study of Bonett’s (2009) meta-analytic model(2012-10) Xie, AolinA key methodological decision in a meta-analysis has traditionally been the choice between the classic fixed-effects (FE) or random-effects (RE) models assumed to underlie effect sizes (see Hedges & Olkin, 1985). Recent work has criticized these models because of the implausibility of their underlying assumptions (Bonett, 2008, 2009; Hunter & Schmidt, 2000). Bonett (2009a) proposed a modified FE model and recommended using contrasts to compare mean effect sizes among levels of discrete moderators. This study empirically investigated the behavior of the Bonett (2009a) modified FE model and the classic FE model for interval estimation and hypothesis testing of effect size contrasts. The results suggested that the two models performed similarly well with normally distributed data. The Bonett model was robust to nonnormality combined with unequal within-study variances and unequal within-study sample sizes, whereas the classic FE model showed inflated type I error rates and lower statistical power under these conditions.Item The etiology of hematologic malignancies in children and adolescents: Pre- and postnatal factors.(2010-03) Linabery, Amy Marie DeVriesLittle is known about the etiology of most pediatric hematologic malignancies, although there is evidence for prenatal initiation of leukemogenesis for many cases. The current body of research, a series of three complementary studies, evaluated the potential for unbiased measurement of prenatal exposures through retrieval of existing biospecimens and examined associations between pre- and postnatal exposures and pediatric/adolescent leukemia. The first study assessed the feasibility of retrospective collection of residual neonatal blood spots (NBS) for 947 childhood/adolescent leukemia and lymphoma cases from state newborn screening programs nationwide. Biological mothers were also asked to complete self-administered questionnaires regarding prenatal exposures, personal and family history of atopic disease, and selected demographic factors. Overall, 37% of families provided consent for NBS release and 41% of mothers completed questionnaires. Consenting cases were born in 39 states and 46 NBS were obtained from 5 states (CA, NY, MI, TX, and WA). NBS storage/release policies are rapidly evolving; requests are pending in states involved in litigation (MN), reviewing policies (NJ), and reviewing this study (MA). Currently, population-based NBS studies can be conducted in a limited number of states; fortunately, most of these have large populations to provide reasonable pediatric case and control groups. In the second study, the largest of its kind, the association between self-reported prenatal vitamin supplementation and infant leukemia was examined, since folic acid is postulated to play a preventative role in the pathogenesis of childhood leukemia, particularly among ALL cases. After adjustment for race/ethnicity and income, there was little evidence supporting associations between periconceptional vitamin use (OR = 0.89, 95% CI: 0.64-1.24), use after knowledge of pregnancy (OR = 0.78, 95% CI: 0.48-1.28), or use in all periods (OR = 0.84, 95% CI: 0.62-1.14) and infant leukemia. These results may be attributable to high rates of folic acid supplementation in the study population, including personal vitamin use and national folic acid fortification programs implemented in the U.S. and Canada early in the study period. Atopic disease is hypothesized to be protective for several malignancies. In the third study, meta-analysis was performed to summarize and quantify the risk of acute leukemia associated with atopic disease in children and adolescents and to identify sources of heterogeneity in the existing literature. Inverse associations were observed for ALL and atopy overall (OR = 0.69, 95% CI: 0.54-0.89)), and for asthma (OR = 0.79, 95% CI: 0.61-1.02), eczema (OR = 0.74, 95% CI: 0.58-0.96), and hay fever (OR = 0.55, 95% CI: 0.46-0.66) examined separately. ORs for ALL differed across strata of study design, exposure data source, and latency period, indicating these factors impact study results. Although these results should be interpreted cautiously given the modest number of studies, substantial heterogeneity, and potential exposure misclassification, they are useful in designing future research.Item Evidence-based reading instruction for English language learners in preschool through sixth grades: a meta-analysis of group design studies.(2009-08) Han, InsoonThe purpose of the study was to synthesize research studies that examined reading instruction for English language learners (ELL) in preschool through sixth grades. Specific goals were to determine the availability of reading instruction for ELLs, the effects of that instruction, and which instructional programs can be considered evidence-based. An extensive search of the research studies identified 29 studies employing group design published in peer-reviewed journals since 1967, which yielded 44 samples with a total of 225 effect sizes. Findings revealed that at both tier 1 and 2, there are more than 10 instructional programs that address phonemic awareness and phonics instruction at preschool to 2nd grade levels, but there were no phonemic awareness and phonics instruction for third to sixth graders. The overall effect of reading instruction was moderate, with a mean ES of 0.50. HLM revealed that factors strengthen the effect were: English as a language of intervention; a session lasted 45 min or less; upper grade level; single grade; average or higher SES; and lower study quality. Three evidence-based or promising practices from 13 programs were identified; Keyword method, Proactive Reading and Peer-Assisted Learning Strategies. The research community should continue to reinforce efforts to improve the quality of research while seeking strong support for rigorous research from policy makers to empower ELL students who are otherwise likely to be at-risk readers by providing them with evidence-based reading instruction.Item Examination of the Effectiveness of Physical Activity Interventions on the Wellbeing of Caregivers of Older Adults: A Meta-Analysis(2021-06) Marshall, ElaineCaregivers of older adults afflicted with a variety of chronic physical and mental health conditions provide vital support and assistance for this growing population. Although essential, many individuals in this time-consuming role are unprepared older adults themselves, which creates significant burdens on their own mental and physical health. Caregivers are at risk for depression, loneliness, and reduced health related to chronic stress. Evidence suggests that physical activity (PA) interventions alleviate aspects of this burden and psychological distress, as well as provide benefits to physical health. However, there are notable limitations in the previous reviews that have attempted to synthesize the evidence for the benefits of PA interventions. Using meta-analytic methodology, this study investigated and quantified the impact of PA interventions on different domains of mental and physical health for caregivers of older adults. A comprehensive search yielded 25 controlled studies. PA interventions led to small-to-medium effects on mental health, with the most notable impact on quality of life. PA interventions led to trivial effects on physical health, with small but significant effects found for mobility outcomes. Moderator analyses revealed that yoga interventions, study quality, and duration of interventions had significant moderating effects. PA interventions appear to be effective for improving caregiver health, particularly in relation to psychological health. Further high-quality research using standardized measures for health domains is needed to determine the type, format, and length of PA interventions that best serve different caregiving populations.Item Exploration Of Primitive Endoderm Cells With Transcriptome Analysis(2016-11) Cho, Dong SeongStem cells hold great clinical potentials for regenerative medicine. Pluripotent stem cells can give rise to any adult cell type. However, pluripotent stem cells have risk of tumor formation and have limitations because of their growth properties. Despite their potentials for therapeutic application, pluripotent stem cells may not be the most suitable for manufacturing process. The derivation of multipotent adult progenitor cells (MAPCs) from rodent bone marrow suggested that these cell types have more amenable properties for manufacturing process than pluripotent stem cells. Especially, rat MAPCs (rMAPCs) can differentiate into multiple lineages including hepatocyte-like cells, β-cell like cells, and mesodermal cells. However, they are not pluripotent and have less risk of tumor formation than pluripotent stem cells. In addition, because MAPCs can be cultivated as single cells, they are less vulnerable than pluripotent stem cells for robust expansion for potential clinical application. Although rMAPCs were derived from rat bone marrow, they resemble the cells in primitive endoderm (PrE) of mouse embryos. Here I showed that a similar population of nascent PrE cells can be derived from pluripotent rat embryonic stem cells (rESCs) by culturing in rMAPC medium conditions, and term these cells converted (c)HypoSCs. Like rMAPCs, cHypoSCs can readily differentiate towards cells with hepatic and mesoderm features in vitro, and generate extraembryonic endoderm in vivo. Transcriptome analysis and mass cytometry further showed that cHypoSCs exhibit nascent PrE gene expression properties that are similar to those of rMAPCs. Cross-species meta-analysis with single-cell transcriptome data confirmed that cHypoSCs are similar to early PrE cells of the mouse blastocyst, while rodent ESCs are similar to early epiblast (EPI) cells. Along with this finding, transcriptome analysis of human in vivo PrE cells and EPI cells uncovered potential culture conditions to derive human nascent in vitro PrE cells from human pluripotent stem cells. We demonstrated the potential of differentiation capacity of human pluripotent stem cells to nascent PrE cells using the identified culture conditions. This study will elucidate the underlying mechanisms of PrE differentiation, and will facilitate the derivation of potentially suitable type of cells for therapeutic application.Item Innovative Statistical Methods for Meta-analyses with Between-study Heterogeneity(2022-06) Xiao, MengliTo assess the benefits and harms of medical interventions, meta-analysis plays an important role in combining results from multiple studies. While the notion of combining independent results is motivated by similarities between studies, a pooled estimate may be insufficient in the presence of between-study heterogeneity in a meta-analysis. The sources of between-study heterogeneity come from studies being: 1) different and unrelated (possibly due to a mixture of non-replicable study findings); 2) different but similar (i.e., drawn from the same distribution); or 3) susceptible to modeling using covariates. In the first, studies do not replicate each other, and meta-analysis is not considered an option. In the second, a random-effects model may be used to reflect the similarity of studies, and in the third, a meta-regression analysis is suggested. To differentiate the first from the others, it is essential to develop a statistical framework establishing whether multiple studies give sufficiently similar results, i.e., replicate each other, before undertaking a meta-analysis. However, traditional meta-analysis approaches cannot effectively distinguish whether the between-study difference is from non-replicability or unknown study-specific characteristics. No rigorous statistical methods exist to characterize the non-replicability of multiple studies in a meta-analysis. In Chapter 2, we introduce a new measure, the externally standardized residuals from a leave-m-studies-out procedure, to quantify replicability. We also explore its asymptotic properties and use extensive simulations and three real-data studies to illustrate this measure's performance. We also provide the R package "repMeta" to implement the proposed approach. The remainder of this dissertation concerns scenarios when substantial heterogeneity still exists among replicable studies in a meta-analysis. Such heterogeneity may or may not decrease by incorporating available covariates in a meta-analysis, given that the sources of effect heterogeneity are commonly unknown and unmeasured. A proxy for those unknown and unmeasured factors may still be available in a meta-analysis, namely the baseline risk. Chapter 3 proposes using the bivariate generalized linear mixed-effects model (BGLMM) to 1) account for the potential correlation of the baseline risk with the treatment effect measure, and 2) obtain estimated effects conditioning on the baseline risk. We demonstrate a strong negative correlation between study effects and the baseline risk, and the conditional effects notably vary with baseline risks. Chapter 4 reinforces the suggestion that a meta-analysis should model the heterogeneity in effect measures with respect to baseline risks and study conditions. It finds that two commonly-used binary effect measures, the odds ratio (OR) and risk ratio (RR), have a similar dependence on the baseline risk in 20,198 meta-analyses from the Cochrane Database of Systematic Reviews, a leading source of healthcare evidence. This empirical evidence contrasts with a false argument that OR does not vary with study conditions. We illustrate that understanding effect heterogeneity is essential to patient-centered practice in an actual meta-analysis of the interventions addressing the chronic hepatitis B virus infection.Item Long-term Comparative Effectiveness of Rheumatoid Arthritis Treatment Strategies(2013-08) Jalal, HawreRheumatoid arthritis (RA) is a chronic debilitating disease characterized by progressive joint damage, reduced quality of life, loss of productivity and premature death. It affects 1% of the adult US population, and is one of the most demanding diseases on our healthcare resources. Biologic disease modifiers are new drugs that provide hope to improve the course of RA; however, biologics are among the most expensive specialty drugs. Although the treatment costs of RA have recently increased with the introduction of biologics, most of the economic and societal impacts are due to consequences of RA rather than direct treatment costs. Thus, the cost-effectiveness of biologics in RA is of high priority as recognized by many agencies including the National Institute of Health. This thesis focuses on three limitations of the current cost-effectiveness analyses (CEA) of biologics in RA. First, Most CEAs are based on randomized clinical trials (RCT) that are rarely applicable to real-life clinical practice. This thesis examines the long-term comparative clinical- and cost-effectiveness of biologics using clinical practice data from a large registry of RA patients (The National Data-Bank of Rheumatic Diseases). Second, we lack a meta-analytical approach specific to CEAs, and previous tools are deemed inappropriate. This thesis presents a novel approach of meta-analysis specific to CEAs. Using this tool we examine if prior CEAs of biologics in RA are consistent. Third, due to the biologics' high costs, RA treatment guidelines often recommend biologics as second line agents after nonbiologics. However, early aggressive treatment is crucial to avoid permanent joint damage. In this thesis we use Markov decision processes (MDP) as an innovative approach to identify the optimal timing of biologics in RA. The results from this analysis have significant policy, clinical and methodological implications. This work provides important insights into the comparative effectiveness of biologics in RA from a US societal perspective, which can influence health policy and medical insurance coverage decisions. Methodologically, the proposed meta-analytical approach can be applied to other conditions, and have the potential to reconcile the inconsistencies in published CEAs and improve the quality of future studies.Item Meta-Analyses of Personality and Cognitive Ability(2014-08) Stanek, KevinPersonality and cognitive ability are the two most important domains of individual differences in terms of their breadth and impact on human behavior. An abundance of research has examined the relations between these domains, but previous empirical reviews of this literature have suffered from three key deficiencies. First, previous meta-analyses of personality and cognitive ability relied on biased, insular strategies to identify and obtain the relevant literature. This limitation has resulted in relatively small numbers of relatively homogeneous studies being used to understand each relation. Second, previous reviews were organized around less-comprehensive and less-detailed construct frameworks, especially in the personality domain. This limitation made previous findings for various personality trait categories liable to influence from unspecified mixtures of variance attributable to multiple constructs. This limitation also precluded a systematic approach to examining or understanding relations at the lower, aspect and facet levels of personality. Finally, previous reviews of personality and cognitive ability lacked empirical keys/maps for matching constructs across measures. The current meta-analyses endeavored to remedy these deficiencies and fully elucidate the relations between personality and cognitive ability by employing a more comprehensive primary source identification strategy and more empirically-grounded frameworks for organizing the personality and cognitive ability domains. Personality and cognitive ability are not entirely independent domains of individual differences and the overlap extends beyond commonly recognized personality traits. Results highlight the importance of: (1) considering personality aspects and facets, (2) distinguishing general and specific cognitive abilities, and (3) considering the global Big Five dimensions, aspects, facets, and compounds jointly. Openness/Intellect, Agreeableness, and Conscientiousness results all contained findings that differed by aspect. Facets of personality also displayed relations with cognitive ability constructs that were disparate from the relations observed at the global factor and even at the aspect level. Similarly, results for several personality constructs indicated that distinguishing between cognitive abilities at the general factor and specific component levels was important. Overall, the findings suggest even more points of overlap between cognitive abilities and personality constructs than previously recognized.Item The nomological network of self-efficacy and psychometric properties of its general and specific measures(2013-02) Seltzer, Benjamin K.Since its proposal in 1977, self-efficacy (SE) has been applied to almost every behavioral undertaking imaginable. Over 30,000 studies have been conducted on SE since its introduction in 1977, and even meta-analyses exist in abundance. Unfortunately, the self-efficacy literature tends to suffer from several common oversights: 1) neglecting measurement properties of self-efficacy scales; 2) inappropriate compartmentalization of self-efficacy by domain; and 3) inappropriate categorization of criteria/outcomes of interest. Accordingly, the goal of the present research was to address the criticisms raised above through meta-analyses of five distinct areas: 1) the reliability of scores from SE scales; 2) the convergence of SE scales within and across behavioral domains; 3) the potentially differential relationships between SE scales and personality traits; 4) the potentially differential correlations between SE scales and cognitive ability; and 5) the potentially differential correlations between SE scales and outcomes. General and specific SE scales were examined for potentially differing relationships with variables of interest. Scales of self-efficacy exceeded basic standards of internal consistency reliability (though these scales were most consistent when at least 5 - 8 items in length) and displayed strong relationships with one another, even at differing levels of specificity and across behavioral domains. Additionally, self-efficacy scales demonstrated similar patterns of relationships with personality across domains. While measures of self-efficacy displayed more variable patterns of relationships with specific criteria, most scales - even those not tailored for the specific criterion - still functioned as acceptable predictors of academic and organizational performance.Item Relations between CBM (Oral Reading and Maze) and Reading Comprehension on State Achievement Tests: A Meta-Analysis(2017-09) Shin, JaehyunThe purpose of this study was to examine the validity of two widely used Curriculum-Based Measurement (CBM) in reading – oral reading and maze task – in relation to reading comprehension on state tests using a meta-analysis. A total of 61 studies (132 correlations) were identified across Grades 1 to 10. A random-effects meta-analysis was conducted to estimate the average correlations between the two CBMs and reading comprehension on state tests, and to analyze the effects of potential moderating variables (characteristics of study, students, CBM, and state tests). Results revealed that the average correlation for oral reading was significantly larger than that for maze when all grade levels were included together in the analysis. When grade levels were separated, the difference between average correlations was only at the higher grades (Grades 4-10), favoring oral reading. In terms of correlations by grade level, oral reading and maze showed a similar pattern; that is, correlations were comparable across elementary grades, but decreased for secondary grades. In addition to the type of CBM and grade level differences, type of publication, development type of state tests (commercial versus state-developed), and time interval between CBM and state tests were significant sources of variance in correlations. Implications for research and educational practice are discussed highlighting the somewhat different conclusions from previous literature, especially regarding the use of CBM for older students.Item Statistical methods for meta-analysis(2017-05) Lin, LifengMeta-analysis has become a widely-used tool to combine findings from independent studies in various research areas. This thesis deals with several important statistical issues in systematic reviews and meta-analyses, such as assessing heterogeneity in the presence of outliers, quantifying publication bias, and simultaneously synthesizing multiple treatments and factors. The first part of this thesis focuses on univariate meta-analysis. We propose alternative measures to robustly describe between-study heterogeneity, which are shown to be less affected by outliers compared with traditional measures. Publication bias is another issue that can seriously affect the validity and generalizability of meta-analysis conclusions. We present the first work to empirically evaluate the performance of seven commonly-used publication bias tests based on a large collection of actual meta-analyses in the Cochrane Library. Our findings may guide researchers in properly assessing publication bias and interpreting test results for future systematic reviews. Moreover, instead of just testing for publication bias, we further consider quantifying it and propose an intuitive publication bias measure, called the skewness of standardized deviates, which effectively describes the asymmetry of the collected studies’ results. The measure’s theoretical properties are studied, and we show that it can also serve as a powerful test statistic. The second part of this thesis introduces novel ideas in multivariate meta-analysis. In medical sciences, a disease condition is typically associated with multiple risk and protective factors. Although many studies report results of multiple factors, nearly all meta-analyses separately synthesize the association between each factor and the disease condition of interest. We propose a new concept, multivariate meta-analysis of multiple factors, to synthesize all available factors simultaneously using a Bayesian hierarchical model. By borrowing information across factors, the multivariate method can improve statistical efficiency and reduce biases compared with separate analyses. In addition to synthesizing multiple factors, network meta-analysis has recently attracted much attention in evidence-based medicine because it simultaneously combines both direct and indirect evidence to compare multiple treatments and thus facilitates better decision making. First, we empirically compare two network meta-analysis models, contrast- and arm-based, with respect to their sensitivity to treatment exclusions. The arm-based method is shown to be more robust to such exclusions, mostly because it can use single-arm studies while the contrast-based method cannot. Then, focusing on the currently popular contrast-based method, we theoretically explore the key factors that make network meta-analysis outperform traditional pairwise meta-analyses. We prove that evidence cycles in the treatment network play critical roles in network meta-analysis. Specifically, network meta-analysis produces posterior distributions identical to separate pairwise meta-analyses for all treatment comparisons when a treatment network does not contain cycles. This equivalence is illustrated using simulations and a case study.Item A study of the validity of the eating disorder examination.(2010-06) Berg, Kelly ChristinaThe Eating Disorder Examination (EDE), an investigator-based interview, and the questionnaire version of the EDE (EDE-Q) are considered the preeminent assessments of eating disorder symptoms. Despite their status as gold-standard eating disorder assessments, research on the psychometric properties of these measures is limited. The current studies aimed to enhance these data, specifically with regard to the convergence of the EDE and EDE-Q and the validity of the EDE in the assessment of binge eating. For the first study, a meta-analysis of 15 studies on the convergent validity of the EDE and EDE-Q using correlation coefficients and Cohen's d was conducted. The results demonstrated convergence between the EDE and EDE-Q for the assessment of cognitive symptoms and compensatory behaviors, but limited convergence for the assessment of binge eating. A second study compared the frequency of binge eating recalled on the EDE to that reported in Daily Food Records (DFRs) by 34 participants. The results demonstrated convergence between the EDE and DFRs for the assessment of Objective Bulimic Episodes and Total binge frequency in Month 1. These studies suggest that the EDE and EDE-Q assess similar constructs, but indicate that they should not be used interchangeably. Additionally, the data provide preliminary support for the use of the EDE in the assessment of binge eating during the past month.Item Utilizing Reduced-Oil Corn Distillers Grains with Solubles in Finishing Beef Cattle Diets(2015-10) Hohertz, AlexAs ethanol producers continue to seek greater value from a grain, adoption of oil extraction via front-end fractionation of the whole kernel prior to fermentation or through back-end centrifugation of the thin stillage stream contributes to varying nutrient composition and feeding value of distillers grains with solubles (DGS). The impact of oil extraction on finishing feedlot cattle performance and resulting energy values is an item of interest to cattle feeders and nutritionists. Thus, two studies were conducted: a 181-d finishing feedlot experiment and a meta-analysis of published data, to determine effects of oil extraction on finishing cattle performance and resulting energy values. Effects of feeding reduced-fat (RF) modified wet distillers grains with solubles (MDGS) on finishing cattle performance, carcass characteristics, and resulting energy values were evaluated in Study 1. Linear contrasts in experiment 1 demonstrated that feeding RF MDGS at 30 and 45% inclusion (high inclusion) led to cattle consuming more DM than feeding full-fat (FF) or RF MDGS at 15% inclusion. There were no significant differences in all other performance variables, carcass characteristics or resulting energy values. Study 2 was conducted utilizing a meta-analysis approach to determine the energy value of oil extracted corn distillers grains with solubles (DGS) in finishing feedlot cattle diets. Results from Study 2 revealed that feeding FF DGS resulted in greater ADG compared to feeding RF DGS or control diets, and feeding RF DGS resulted in greater ADG compared to feeding control diets. At increasing DGS inclusion, feeding FF DGS led to lower DMI than feeding RF DGS. Feeding DGS at moderate or high inclusion, regardless of fat content, resulted in greater feed conversion efficiency compared to feeding control diets. At high inclusion, feeding FF DGS led to greater feed conversion efficiency than feeding RF DGS. Feeding FF DGS at moderate or high inclusion or RF DGS at moderate inclusion resulted in greater observed ME concentration compared to feeding control diets. One unit of ether extract (EE) from DGS contributed 0.06 Mcal ME/kg DM to dietary ME. Results of the meta-analysis demonstrated that reducing oil content of corn DGS reduced energy value of the DGS, thus corrections to energy content of currently available DGS are required. A third experiment was conducted to characterize the nutrient content of corn plant components at various corn crop harvest endpoints. Through reproductive stages of development, corn plant DM increased until dry corn grain harvest. Concurrently; NDF, ADF, and CP concentrations decrease as the plant matures while ether extract (EE) increases once the plant reaches physiological maturity. When concluding the results of this experiment in terms of a producer growing corn as a feed resource for cattle, it is recommended that scouting of corn fields begins once pollination occurs. By beginning to scout fields at the beginning of reproduction, producers can then closely monitor plant DM in order to harvest various corn crop endpoints at their ideal time.