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COLAGROSSI, MARCO. "META-ANALYSIS AND META-REGRESSION ANALYSIS IN ECONOMICS: METHODOLOGY AND APPLICATIONS." Doctoral thesis, Università Cattolica del Sacro Cuore, 2017. http://hdl.handle.net/10280/19697.
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A partire dagli anni ’80, la diffusione dei metodi statistici, abbinata ai progressi nelle capacità computazionali dei personal computers, ha progressivamente facilitato i ricercatori nel testare empiricamente le proprie teorie. Gli economisti sono diventati in grado di eseguire milioni di regressioni prima di pranzo senza abbandonare le proprie scrivanie. Purtroppo, ciò ha portato ad un accumulo di evidenze spesso eterogenee, quando non contradditorie se non esplicitamente in conflitto. Per affrontare il problema, questa tesi fornirà una panoramica dei metodi meta-analitici disponibili in economia. Nella prima parte verranno introdotte le intuizioni alla base dei modelli gerarchici a fattori fissi e casuali capaci di risolvere le problematicità derivanti dalla presenza di osservazioni non indipendenti. Verrà inoltre affrontato il tema dell’errore sistematico di pubblicazione in presenza di elevata eterogeneità tra gli studi. La metodologia verrà successivamente applicata, nella seconda e terza parte, a due diverse aree della letteratura economica: l’impatto del rapporto banca-impresa sulle prestazioni aziendali e il dibattito sulla relazione fra democrazia e crescita. Mentre nel primo caso la correlazione negativa non è influenzata da fattori specifici ai singoli paesi, il contrario è vero per spiegare l’impatto (statisticamente non significativo) delle istituzioni democratiche sullo sviluppo economico. Quali siano questi fattori è però meno chiaro; gli studiosi non hanno ancora individuato le co-variate – o la corretta misurazione di esse – capaci di spiegare questa discussa relazione.Starting in the late 1980s, improved computing performances and spread knowledge of statistical methods allowed researchers to put their theories to test. Formerly constrained economists became able [to] run millions of regressions before lunch without leaving their desks. Unfortunately, this led to an accumulation of often conflicting evidences. To address such issue, this thesis will provide an overview of the meta-analysis methods available in economics. The first paper will explain the intuitions behind fixed and random effects models in such a framework. It will then detail how multilevel modelling can help overcome hierarchical dependence issues. Finally, it will address the problem of publication bias in presence of high between-studies heterogeneity. Such methods will be then applied, in the second and third papers, to two different areas of the economics literature: the effect of relationship banking on firm performances and the democracy and growth conundrum. Results are far-reaching. While in the first case the documented negative relation is not driven by country-specific characteristics the opposite is true for the (statistically insignificant) impact of democratic institutions on economic growth. What these characteristics are is, however, less clear. Scholars have not yet found the covariates - or their suitable proxies - that matter to explain such much-debated relationship.
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COLAGROSSI, MARCO. "META-ANALYSIS AND META-REGRESSION ANALYSIS IN ECONOMICS: METHODOLOGY AND APPLICATIONS." Doctoral thesis, Università Cattolica del Sacro Cuore, 2017. http://hdl.handle.net/10280/19697.
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A partire dagli anni ’80, la diffusione dei metodi statistici, abbinata ai progressi nelle capacità computazionali dei personal computers, ha progressivamente facilitato i ricercatori nel testare empiricamente le proprie teorie. Gli economisti sono diventati in grado di eseguire milioni di regressioni prima di pranzo senza abbandonare le proprie scrivanie. Purtroppo, ciò ha portato ad un accumulo di evidenze spesso eterogenee, quando non contradditorie se non esplicitamente in conflitto. Per affrontare il problema, questa tesi fornirà una panoramica dei metodi meta-analitici disponibili in economia. Nella prima parte verranno introdotte le intuizioni alla base dei modelli gerarchici a fattori fissi e casuali capaci di risolvere le problematicità derivanti dalla presenza di osservazioni non indipendenti. Verrà inoltre affrontato il tema dell’errore sistematico di pubblicazione in presenza di elevata eterogeneità tra gli studi. La metodologia verrà successivamente applicata, nella seconda e terza parte, a due diverse aree della letteratura economica: l’impatto del rapporto banca-impresa sulle prestazioni aziendali e il dibattito sulla relazione fra democrazia e crescita. Mentre nel primo caso la correlazione negativa non è influenzata da fattori specifici ai singoli paesi, il contrario è vero per spiegare l’impatto (statisticamente non significativo) delle istituzioni democratiche sullo sviluppo economico. Quali siano questi fattori è però meno chiaro; gli studiosi non hanno ancora individuato le co-variate – o la corretta misurazione di esse – capaci di spiegare questa discussa relazione.Starting in the late 1980s, improved computing performances and spread knowledge of statistical methods allowed researchers to put their theories to test. Formerly constrained economists became able [to] run millions of regressions before lunch without leaving their desks. Unfortunately, this led to an accumulation of often conflicting evidences. To address such issue, this thesis will provide an overview of the meta-analysis methods available in economics. The first paper will explain the intuitions behind fixed and random effects models in such a framework. It will then detail how multilevel modelling can help overcome hierarchical dependence issues. Finally, it will address the problem of publication bias in presence of high between-studies heterogeneity. Such methods will be then applied, in the second and third papers, to two different areas of the economics literature: the effect of relationship banking on firm performances and the democracy and growth conundrum. Results are far-reaching. While in the first case the documented negative relation is not driven by country-specific characteristics the opposite is true for the (statistically insignificant) impact of democratic institutions on economic growth. What these characteristics are is, however, less clear. Scholars have not yet found the covariates - or their suitable proxies - that matter to explain such much-debated relationship.
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Pan, Jingwen. "Labyrinthulomycetes diversity meta-analysis." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/56302.
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Labyrinthulomycetes are a group of ubiquitous stramenopiles that inhabit a wide range of habitats and play important ecological roles as nutrient recyclers and sometimes disease causing agents. Even though they have had a long history of being studied, their diversity has not yet been fully explored. The lack of a comprehensive reference database with up-to-date phylogeny also hinders any pursuits in understanding the ecological distribution of this group. This study was designed with the purpose of constructing a curated reference database and a phylogenetic tree based on existing 18S rDNA data, and then using this database to uncover any hidden diversity and novelty among Labyrinthulomycetes and provide a reference guidance for future identification. Using the newly-created reference database, I also analyzed high-throughput environmental sequencing data from two databases. My results reveal extensive diversity within the Labyrinthulomycetes, and recover many previously unknown environmental sequences, greatly expanding our knowledge of the ecological distribution of this group. The high-throughput environmental sequencing data analysis also shows some of the newly identified environmental clades to be particularly abundant in the ocean. The phylogenetic framework I have provided in this study, together with the metadata I have compiled, will serve as a useful tool for future ecological and evolutionary studies of this widespread lineage.Science, Faculty of
Botany, Department of
Graduate
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Boykova, Alla. "An introduction to meta analysis." Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/605.
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Jamain, Adrien. "Meta-analysis of classification methods." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413686.
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Gandini, Sara. "Meta-analysis in cancer epidemiology." Thesis, University of Birmingham, 2004. http://etheses.bham.ac.uk//id/eprint/251/.
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A published meta-analysis on breast cancer and vegetables and fruit consumption was described to present a methodology used on meta-analysis in Epidemiology. Meta-analysis confirmed the association between intake of vegetables (RR=0.74; 95%CI 0.65-0.84) and, to a lesser extent, fruit and breast cancer risk (RR=0.93; 95%CI 0.79-1.09). Using this methodology, present in a peer-reviewed journal, a systematic meta-analysis on melanoma was conducted extracting RRs from published studies. Fully adjusted estimates were obtained from those studies, when available; RRs adjusted for confounders not related to sun exposure, such as naevi, were considered for sun exposure and sunburns pooled estimates. Pooled estimates were obtained for all main risk factors for melanoma: sun exposure (total, intermittent and chronic), sunburns (in childhood and in adulthood), indicators of actinic damage, family history of melanoma and phenotype characteristics. Investigation of biases and inconsistencies among studies was one of the key phases of the meta-analysis to look for patterns among studies that might explain discrepant findings. The analyses on pigmented lesions and sun exposure showed that the choice of sources of cases and controls influenced significantly the estimate. An indication of a protective effect of chronic sun exposure came from studies that did not include subjects with dermatological problems (significantly different from the other studies: p=0.01). Publication year was an important factor for total sun exposure (p=0.005). Latitude of the study seemed to be an important factor for sunburns (p=0.002) and for high density of freckles (p=0.04). Estimates for hair colour and eye colour adjusted for phenotype and/or photo-type were significantly lower than unadjusted ones (p=0.06 and p=0.06, respectively). This study highlighted how several features of study design, type of analysis, categorization of exposures, study location and populations significantly explained between-study heterogeneity.
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Paterson, Chris Edward. "Progressive relaxation : a meta-analysis /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487332636477408.
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Wise, Joan Catherine. "Bereavement interventions a meta-analysis /." Online full text .pdf document, available to Fuller patrons only, 2003. http://www.tren.com.
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Gen, Sheldon. "Meta-Analysis of Environmental Valuation Studies." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4843.
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Cost-benefit analysis has long been a dominant method of policy analysis. When applied to policies affecting the environment, however, it faced a serious problem. Many policies exert environmental impacts that are external to market transactions, so the values of these impacts resist monetary measurement. This shortcoming in cost-benefit analysis led some researchers to develop indirect and nonmarket methods of valuing environmental goods monetarily. They include the travel cost method, hedonic pricing, and contingent valuation. The popularity of these methods has grown since their inceptions, but so have controversies over their use. Economists and others have taken all sides of the debate over the validity of the methods and their normative implications. These methods popularity and controversies necessitate their critical evaluation. This research fills this need through an extensive meta-analysis of 228 existing environmental valuation studies representing the contemporary practices in each method, and capturing varieties of environmental goods and settings. The analysis tested the convergent validity of the three valuation methods, and measured the moderating effects of select variables. The results show that effect sizes of the hedonic pricing and travel cost methods converge, but contingent valuation produces effect sizes that average 40% to 55% less than the other two methods. This difference varies significantly with the environment good being valued. Other significant moderating variables include the magnitude of the environmental change, the description of the change, and the location of the study. The year of study does not significantly moderate effect sizes. These results supplement descriptive and normative frameworks for environmental valuation described by Barbier (1994), Navrud and Pruckner (1997), and Norton (1995). When the evidence and these frameworks are considered together, the defensible uses of these three valuation methods become very limited. Valuation efforts should focus on multiple dimensions of environmental value, besides economic dimensions, that reflect ecological health and public concerns for the environment.
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Nell, Christopher Warren. "Automating meta-algorithmic analysis and design." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/38247.
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Sophisticated empirical methods based upon automated experimental analysis techniques drive the development of high-performance solvers for an increasing range of problems from industry and academia. However, tools implementing these methods are often difficult to develop and to use. This thesis describes work towards addressing this issue. First, we develop a formal description of meta-algorithmic problems, and use it as the basis for a framework supporting the development and application of a broad class of automated algorithm analysis and design techniques. Second, we describe the High-performance Algorithm Laboratory (HAL), an extensible software implementation of this framework that provides developers and users of automated empirical techniques with support for distributed execution, remote monitoring, data management, and statistical analysis of results. We use HAL to construct a suite of interoperable tools that implement a variety of automated empirical techniques, and demonstrate our approach by conducting a sequence of increasingly complex analysis and design tasks on state-of-the-art solvers for Boolean satisfiability and mixed-integer programming problems.
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Yu, Ka-ki Kevin, and 余嘉棋. "Neuroimaging meta-analysis in neurodevelopmental disorders." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47753171.
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Background and Objectives: ‘Neurodevelopmental disorders’ is often synonymously used with childhood developmental disorders such as autism spectrum disorder (ASD), however, increasingly new lines of evidence from genetics and epidemiology suggests having schizophrenia and bipolar disorder to be included as well. For example, there is a strong tendency for schizophrenia and bipolar disorder to occur in people with ASD and shared aetiological factors such as prenatal infection and maternal vitamin D deficiency during pregnancy have all been linked with increased risks in all three conditions. To investigate into this, I have turned to brain imaging, a technique which has opened up a new horizon for neurobiologists. Typically, neuroimaging studies focus on one disorder, matching patients with healthy volunteers and compare their brain structures volumetric differences. On the other hand, such studies are limited by various factors including small ample size, low power, no psychiatric control group, and sample or design heterogeneity.
Methods: To summarize all the data into a more meaningful biological representation, Anatomical Likelihood Estimation (ALE), a cutting edge meta-analytic approach was applied. The rationale behind ALE is that it identifies brain differences most consistently reported across studies, while filtering away differences that are least documented. In this thesis, a novel application of ALE known as “dual disorder ALE” is introduced, which serves to estimate the extent of brain regional differences implicated in either disorder – in other words, a method to quantify which areas of the brain are more likely to be affected by ASD, schizophrenia or bipolar disorder.
Findings: The analysis is separated into two parts. First, dual disorder ALE technique was applied to investigate the relationship between ASD and first-episode schizophrenia. Data from 25 MRI studies was extracted comprising 660 participants (308 ASD, 352 schizophrenia) and 801 healthy controls. In ASD and FE schizophrenia, there were similar brain differences near the limbic-striato-thalamic circuitry, and distinctive brain differences including amygdala, caudate, frontal and medial gyrus for schizophrenia and putamen for ASD. In the second part comparing bipolar disorder and schizophrenia, data from 651 schizophrenic patients, 540 bipolar patients, and 1438 healthy controls was used, and matched one-to-one by pairing up bipolar disorder studies with corresponding schizophrenia studies to minimize confounders. The ALE result indicated that there are substantial overlaps across the two disorders, with schizophrenia having more extensive brain differences than bipolar disorder.
Conclusions: Both parts of the analysis suggest that there are similar aetiological pressures affecting neurodevelopmental disorders including ASD, schizophrenia and bipolar disorder.published_or_final_version
Psychiatry
Master
Master of Philosophy
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Dwan, Kerry Margaret. "Outcome reporting bias in meta-analysis." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526893.
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Introduction: The increased use of meta-analysis in systematic reviews of healthcare interventions has highlighted several types of bias that can arise during the completion of a randomised controlled trial (RCT). Publication bias has been recognised as a potential threat to the validity of meta-analysis and can make the readily available evidence unreliable for decision making. Until recently, outcome reporting bias (ORB) has received less attention. ORB occurs when outcomes are selectively reported for publication based on their results. This can impact upon the results of a meta-analysis, biasing the pooled treatment effect. Methods: Empirical evidence from a series of cohort studies that have assessed study publication bias and ORB in RCTs is reviewed and summarised. Methods for identifying ORB in a review and trial reports are discussed using several motivating examples. Guidelines are obtained and assessed from worldwide organisations and UK based charities that fund RCTs; with regards to trial registration, protocol adherence and trial publication. Statistical, educational and policy solutions are reviewed. A novel weighted linear regression is used to predict missing outcome data when bias is suspected in a review containing structurally related outcomes. A maximum bias bound previously proposed is further assessed using a simulation study to test the sensitivity of the method when heterogeneity is present. The outcome reporting bias in trials (ORBln study is introduced and the impact ORB has on this cohort of reviews from the Cochrane Library is assessed using the bound for maximum bias. Results: Four empirical studies that examined the association between outcome reporting bias and statistical significance found that statistically significant outcomes were more likely to be completely reported than non-significant outcomes (range of odds ratios: 2.2 to 4.7). Guidelines for 73 organisations and charities were reviewed; only eleven of these organisations or charities mentioned the publication of negative as well as positive outcomes. The simulation study indicates that the bound for maximum bias is a useful approach for reviewers to apply to assess the robustness of the conclusions of a review to ORB and can be applied in the presence of heterogeneity. Assessing the impact of ORB in the cohort of reviews in the ORBIT study indicates that ORB had an impact in 15% of the reviews considered. Conclusions: This work summarises the direct empirical evidence for the existence of study publication bias and ORB. Researchers need to be aware of the problems of both types of bias and efforts should be concentrated on improving the reporting of trials. There is a need to provide more detailed guidance for those conducting and reporting RCTs to help prevent the selective reporting of results. There are several complementary initiatives to either prevent ORB or to reduce the occurrence of ORB. Therefore, with the implementation and development of these solutions it is hoped that in the future ORB will become less of a problem. However, methods that detect ORB and adjust results for ORB can be useful while the initiatives are given time to make an impact.
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Hansen, Michael John. "A meta-analysis of institutional theories." Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/27130.
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Ahmed, Ikhlaaq. "Meta-analysis of risk prediction studies." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/6376/.
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This thesis identifies and demonstrates the methodological challenges of meta-analysing risk prediction models using either aggregate data or individual patient data (IPD). Firstly, a systematic review of published breast cancer models is performed, to summarise their content and performance using aggregate data. It is found that models were not available for comparison. To address this issue, a systematic review is performed to examine articles that develop and/or validate a risk prediction model using IPD from multiple studies. This identifies that most articles only use the IPD for model development, and thus ignore external validation, and also ignore clustering of patients within studies. In response to these issues, IPD is obtained from an article which uses parathyroid hormone (PTH) assay (a continuous variable) to predict postoperative hypocalcaemia after thyroidectomy. It is shown that ignoring clustering is inappropriate, as it ignores potential between-study heterogeneity in discrimination and calibration performance. This dataset was also used to evaluate an imputation method for dealing with missing thresholds when IPD are unavailable, and the simulation results indicate the approach performs well, though further research is required. This thesis therefore makes a positive contribution towards meta-analysis of risk prediction models to improve clinical practice.
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Hernández, Manuel S. (Manuel Segundo). "Meta-analysis of Tokamak reactor designs." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/106768.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Nuclear Science and Engineering, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 55-60).
The long-term interest in nuclear fusion using tokamaks has yielded many published reactor designs. This study performs the first meta-analysis of tokamak reactor designs in an attempt to unveil new understanding not available in the traditional bottom-up method of looking at each design individually. Forty tokamak designs intended to produce significant fusion power at gains above one were identified in the published literature. Thirty-three important parameters describing a tokamak design were compiled by examining the set. The parameters from each design were extracted and placed into a database and plotted against each other to identify trends and outliers. Major outliers include two low aspect ratio designs and two He-3 reactor designs. Two classes are apparent in the database indicating two design philosophies: large major radius (~7 m), high power (~1.8 GW), and low density (~1 * 1020 m-3) designs utilizing superconducting magnets; and small major radius (~2.5 m), low power (~0.2 GW), and high density (~4* 1020 m-3 designs utilizing copper magnets. The former class has longer confinement times, higher plasma current, and lower magnetic field while the latter class tends to have lower gain, higher power per surface area, higher power per volume, and much smaller stored magnetic energies. Between the two sets, the non-dimensional plasma physics parameters are similar. These two basic design strategies have been in practice for the last 40 years. Since tokamak designs were first published, there has been little appreciable change in the mean and design envelope of the major parameters such as major radius, fusion power, magnetic field, and plasma current and of the plasma physics parameters such as beta, safety factor, temperature, density, and confinement time. The lack of significant change suggests that no major technological or physics breakthrough that could radically affect design philosophy has been discovered, and neither design philosophy has dominated. Trade-offs in triple product are apparent as all designs are at similar plasma temperature except He-3 reactors, while confinement time and density vary inversely among designs. The major dependencies on plasma current and size in the experimental confinement time scaling are also apparent. The conservatism inherent in reactor designs can be inferred from plasma physics parameters such as the confinement enhancement factor, normalized beta, and safety factor. The database indicates designers push all plasma physics limits simultaneously instead of individually.
by Manuel S. Hernandez.
S.B.
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Siangphoe, Umaporn. "META-ANALYSIS OF GENE EXPRESSION STUDIES." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/4040.
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Combining effect sizes from individual studies using random-effects models are commonly applied in high-dimensional gene expression data. However, unknown study heterogeneity can arise from inconsistency of sample qualities and experimental conditions. High heterogeneity of effect sizes can reduce statistical power of the models. We proposed two new methods for random effects estimation and measurements for model variation and strength of the study heterogeneity. We then developed a statistical technique to test for significance of random effects and identify heterogeneous genes. We also proposed another meta-analytic approach that incorporates informative weights in the random effects meta-analysis models. We compared the proposed methods with the standard and existing meta-analytic techniques in the classical and Bayesian frameworks. We demonstrate our results through a series of simulations and application in gene expression neurodegenerative diseases.
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Lillard, Richard P. "Dialectical behavior therapy a meta-analysis /." Theological Research Exchange Network (TREN), access this title online, 2005. http://www.tren.com/search.cfm?p088-0127.
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Mease, Alyson Leigh. "Meta-analysis of family therapy research." [Bloomington, Ind.] : Indiana University, 2004. http://wwwlib.umi.com/dissertations/fullcit/3162250.
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Thesis (Ph.D.)--Indiana University, Dept. of Counseling Psychology, 2004.Title from PDF t.p. (viewed Dec. 1, 2008). Source: Dissertation Abstracts International, Volume: 66-01, Section: B, page: 0566. Chair: Thomas L. Sexton.
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Magosi, Lerato Elaine. "Dissecting heterogeneity in GWAS meta-analysis." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:c853f7e7-93de-440c-b57c-fcfc03d3bb86.
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Statistical heterogeneity refers to differences among results of studies combined in a meta-analysis beyond that expected by chance. On the one hand, excessive heterogeneity can diminish power to discover genetic signals; on the other, moderate heterogeneity can reveal important biological differences among studies. Given its double-edged nature, this thesis dissects heterogeneity in genetic association meta-analyses from three vantage points. First, a novel multi-variant statistic, M is proposed to detect genome-wide (systematic) heterogeneity patterns in genetic association meta-analyses. This was motivated by the limited availability of appropriate methodology to measure the impact of heterogeneity across genetic signals, since traditional metrics (Q, I2 and T2) measure heterogeneity at individual variants. Second, given that meta-analyses comprising small numbers of studies typically report imprecise summary effect estimates; GWAS-derived empirical heterogeneity priors are used to improve precision in estimation of average genetic effects and heterogeneity in smaller meta-analyses (e.g. ≤ 10 studies). Third, a critical evaluation of the Han-Eskin random-effects model shows how it can identify small effect heterogeneous loci overlooked by traditional fixed and random-effects methods. This work draws attention to the existence of genome-wide heterogeneity patterns, to reveal systematic differences among the ascertainment criteria of participating studies in a meta-analysis of coronary disease (CAD) risk. Furthermore, simulation studies with the Han-Eskin random-effects model revealed inflated genetic signals at small effect loci when heterogeneity levels were high. However, it did reveal an additional CAD risk variant overlooked by traditional meta-analysis methods. We therefore recommend a holistic approach to exploring heterogeneity in meta-analyses which assesses heterogeneity of genetic effects both at individual variants with traditional statistics and across multiple genetic signals with the M statistic. Furthermore, it is critically important to review forest plots for small effect loci identified using the Han-Eskin random-effects model amidst moderate-to-high heterogeneity (I2 ≥ 40%).
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Toro, Rodriguez Roberto C. "Rethinking meta-analysis: an alternative model for random-effects meta-analysis assuming unknown within-study variance-covariance." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/7037.
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One single primary study is only a little piece of a bigger puzzle. Meta-analysis is the statistical combination of results from primary studies that address a similar question. The most general case is the random-effects model, in where it is assumed that for each study the vector of outcomes T_i~N(θ_i,Σ_i ) and that the vector of true-effects for each study is θ_i~N(θ,Ψ). Since each θ_i is a nuisance parameter, inferences are based on the marginal model T_i~N(θ,Σ_i+Ψ). The main goal of a meta-analysis is to obtain estimates of θ, the sampling error of this estimate and Ψ.
Standard meta-analysis techniques assume that Σ_i is known and fixed, allowing the explicit modeling of its elements and the use of Generalized Least Squares as the method of estimation. Furthermore, one can construct the variance-covariance matrix of standard errors and build confidence intervals or ellipses for the vector of pooled estimates. In practice, each Σ_i is estimated from the data using a matrix function that depends on the unknown vector θ_i. Some alternative methods have been proposed in where explicit modeling of the elements of Σ_i is not needed. However, estimation of between-studies variability Ψ depends on the within-study variance Σ_i, as well as other factors, thus not modeling explicitly the elements of Σ_i and departure of a hierarchical structure has implications on the estimation of Ψ.
In this dissertation, I develop an alternative model for random-effects meta-analysis based on the theory of hierarchical models. Motivated, primarily, by Hoaglin's article "We know less than we should about methods of meta-analysis", I take into consideration that each Σ_i is unknown and estimated by using a matrix function of the corresponding unknown vector θ_i. I propose an estimation method based on the Minimum Covariance Estimator and derive formulas for the expected marginal variance for two effect sizes, namely, Pearson's moment correlation and standardized mean difference. I show through simulation studies that the proposed model and estimation method give accurate results for both univariate and bivariate meta-analyses of these effect-sizes, and compare this new approach to the standard meta-analysis method.
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Alharbi, Ghaleb. "Evidence-based medicine in neuropathic pain : a systematic review, meta-analysis, sequential analysis and network meta-analysis of randomised controlled trials." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/55427/.
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Background Many randomised controlled trials (RCTs) are available to support using different pharmacotherapy agents in the management of various neuropathic pain conditions. However, choosing these pharmacotherapy agents for neuropathic pain is challenging, due to the limited evidence-based knowledge to support the use of different pharmacotherapy agents in different neuropathic pain conditions. Aims The aim of this PhD is to evaluate the efficacy and safety of oral and topical pharmacotherapies for managing neuropathic pain by deriving placebo and active comparative efficacy and safety evidence from RCTs. Methods This research used three approaches to summarise and synthesise evidence from randomised controlled studies including: a systematic review of placebo and active control RCTs to summarise and criticise the current evidence in neuropathic pain; a meta-analysis and sequential analysis of eligible studies to provide a more precise estimate of the overall treatment effects; and a network meta-analysis to estimate the relative effectiveness of the most commonly used interventions in neuropathic pain. Results Systematic review Two hundred placebo and active-controlled trials met the inclusion criteria. A wide range of different treatments were studied in these trials, including anticonvulsants, antidepressants, opioids and topical capsaicin and lidocaine. Most of the included studies were parallel placebo-controlled trials and commonly lasted for 3 to 12 weeks. In addition, the vast majority of the included RCTs were conducted in participants with painful diabetic neuropathy and post-herpetic neuralgia, while only a few trials were conducted in participants with central neuropathic pain conditions. Pairwise meta-analysis Sixty seven trials were eligible for the pairwise meta analysis of efficacy outcomes. Of the anticonvulsants group pregabalin and gabapentin compared with placebo demonstrated efficacy for 50% and 30% pain reduction and global improvement in patients with neuropathic pain. The efficacy of anticonvulsants varied in different types of neuropathic pain. Gabapentin when compared against a placebo was better than a placebo in PHN and PDN, while pregabalin was significantly effective in patients with post-herpetic neuralgia (PHN) and painful diabetic neuropathy (PDN) but not in patients with HIV associated neuropathic pain. Others anticonvulsant agents, such as lamotrigine, valproic acid, topiramate, levetiracetam and oxcarbazepine, were tested in a small number of trials. These did not provide useful benefits compared with a placebo for a 50% and 30% pain reduction. Of the antidepressant group, duloxetine when compared to a placebo demonstrated efficacy for 50% and 30% pain reduction in diabetic neuropathic pain. A few active comparison trials failed to demonstrate superior efficacy of one drug over another for a 50% and 30% reduction in neuropathic pain. Trial sequential analysis To examine the reliability and conclusiveness of the available evidence, trialsequential analysis has been applied in this study. The results show convincing evidence of the efficacy of some interventions (e.g. pregabalin, gabapentin and duloxetine) to reduce pain by 50% in some neuropathic pain conditions (e.g. diabetic neuropathic pain and post-herpetic neuralgia). The continuation of RCTs of pregabalin and duloxetine in diabetic neuropathy and gabapentin in post-herpetic neuralgia is not necessary as there appears to be sufficient evidence of the efficacy of these treatments in the management diabetic neuropathic pain and post herpetic neuralgia. Further RCTs of duloxetine, pregabalin and gabapentin are however required for central neuropathic pain. In contrast, the analysis failed to provide evidence that opioids and high concentration capsaicin demonstrate a 50% pain reduction. Network meta-analysis Twenty-eight trials were eligible for the network meta-analysis. The results incorporating both direct-comparison and indirect-comparison evidence suggested that there is no superiority of duloxetine over amitriptyline, pregabalin and gabapentin in achieving at least a 30% and 50% pain reduction with a treatment duration of 7 to 12 weeks in patients with neuropathic pain conditions, such as diabetic neuropathic pain, postherpetic neuralgia and spinal cord injury. Conclusions In summary, this research has found that some good quality trials provide good evidence regarding the efficacy of duloxetine, pregabalin and gabapentin in a minority of patients with neuropathic pain. Until advancements in developing mechanism-based approaches and improved clinical trial design become available, the routine use of these medications is unlikely to be changed. This may support the hypothesis that traditional RCTs might not be a suitable method of choice to address provisional health questions in routine clinical practice.
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Rustenbach, Stephan Jeff. "Metaanalyse : eine anwendungsorientierte Einführung /." Bern ; Seattle : Hans Huber, 2003. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=009805594&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Chung, Yeon Chang. "Meta analysis on high quality recruiting enlistments." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA303812.
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Storrings, Deborah A. "Attrition in distance education a meta-analysis /." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2005. http://wwwlib.umi.com/cr/syr/main.
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Fingeret, Michelle Cororve. "Eating disorder prevention research: a meta-analysis." Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/2258.
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The purpose of this study was to quantitatively evaluate the overall effectiveness of eating disorder prevention programs and to investigate potential moderating variables that may influence the magnitude of intervention effects. Meta-analysis was used to conduct a comprehensive and systematic analysis of data across 46 studies. Effect size estimates were grouped into outcome sets based on the following variables: knowledge, general eating pathology, dieting, thin-ideal internalization, body dissatisfaction, negative affect, and self-esteem. Q statistics were used to analyze the distribution of effect size estimates within each outcome set and to explore the systematic influence of moderating variables. Results revealed large effects on the acquisition of knowledge and small net effects on reducing maladaptive eating attitudes and behaviors at posttest and follow-up. These programs were not found to produce significant effects on negative affect, and there were inconsistent effects on self-esteem across studies. Population targeted was the sole moderator that could account for variability in effect size distributions. There was a tendency toward greater benefits for studies targeting participants considered to be at a relatively higher risk for developing an eating disorder. Previous assumptions regarding the insufficiency of "one-shot" interventions and concerns about the iatrogenic effects of including information about eating disorders in an intervention were not supported by the data. These findings challenge negative conclusions drawn in previous review articles regarding the inability of eating disorder prevention programs to demonstrate behavioral improvements. Although these findings have implications for the prevention of eating disorders, it was argued that a clear link between intervention efficacy and a decreased incidence of eating disorders was not demonstrated. Rather, only direct information was offered about the ability to influence eating disorder related knowledge, attitudes, and behaviors. Specific recommendations related to intervention content, reasonable goals/expectations, and outcome criteria were offered for improving research in this area.
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Dogo, Samson Henry. "Some statistical problems in sequential meta-analysis." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59244/.
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The objective of meta-analysis is to combine results from several independent studies in order to make evidence more generalisable and provide evidence base for decision making. However, recent studies show that the magnitude of effect size estimates reported in many areas of research have significantly changed over time. These temporal trends can be dramatic and even lead to the loss or gain of the statistical significance of the cumulative treatment effect (Kulinskaya and Koricheva, 2010). Standard sequential methods including cumulative meta-analysis, sequential meta-analysis, the use of quality control charts and penalised z-test have been proposed for monitoring the trends in meta-analysis. But these methods are only effective when monitoring in fixed effect model (FEM) of meta-analysis. For random-effects model (REM), the analysis incorporates the heterogeneity variance, t2 and its estimation creates complications. This thesis proposes the use of a truncated CUSUM-type test (Gombay method) for sequential monitoring in REM, and also examines the effect of accumulating evidence in meta-analysis. Simulations show that the use of Gombay method with critical values derived from asymptotic theory does not control the Type I error. However, the test with bootstrap-based critical values (retrospective Gombay sequential bootstrap test for REM) leads to a reduction of the difference between the true and nominal levels, and thus constitutes a good approach for monitoring REM. Application of the proposed method is illustrated using two meta-analytic examples from medicine. Two kinds of bias associated with accumulating evidence, termed \sequential decision bias" and \sequential design bias" are identified. It was demonstrated analytically and by simulations that both types of sequential biases are non negligible. Simulations also show that sequential biases increase with increased heterogeneity.
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Connolly, James J. "Affectivity and job satisfaction: a meta-analysis." FIU Digital Commons, 1998. http://digitalcommons.fiu.edu/etd/2423.
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The goal of this investigation was to examine the affective determinants of job satisfaction. Correlations between affectivity and job satisfaction measures were examined by cumulating research findings across studies. Measurement of affectivity in this study focused on five constructs, (1) negative affectivity, (2) positive affectivity, (3) affective disposition, (4) positive & negative affectivity, (5) all affectivity measures combined. The correlations between these five constructs and job satisfaction were meta-analyzed. The mean correlation corrected for coefficient alpha in both the affectivity and job satisfaction measures were: .49 for positive affectivity (N= 3,326, k= 15), -. 33 for negative affectivity (N= 6,028, k= 25), .36 for affective disposition (N= 1,415, k= 7), .39 for positive & negative affectivity (N= 9,354, k= 40), and .38 for all measures of affectivity combined (N= 10,769, k= 47). Results indicated that 10% - 25% of variance in job satisfaction could be due to individual differences in affectivity. No strong moderator variables were found. Implications for a Dispositional and situational source of job satisfaction are discussed.
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Fanaswala, Mustafa H. "Meta-level pattern analysis for target tracking." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52813.
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Classical target tracking operates on a fast time-scale (order of seconds) during which target dynamics are constrained by the physical laws of motion. This dissertation is motivated by pattern analysis on a meta-level (order of minutes or larger) during which the intent of a target manifests. On such a coarse time-scale, Markovian
models quantifying the physical laws of motion are not useful in detecting anomalous behavior. This is due to the hierarchical nature of plans and goal-oriented targets. In this dissertation, several novel stochastic models are devised to capture long-range dependencies within target trajectories for the joint purpose of classification and enhanced tracking. The behavior of targets on the meta level is captured through both positional features (destination) as well as movement patterns (shape). Such features are used with context-free grammar models and reciprocal Markov models (one dimensional Markov random fields) for modeling spatial trajectories with a known end point. The intent of a target is assumed to be a function of the shape of the trajectory it follows and its intended destination. The stochastic grammar models developed are concerned with trajectory shape classification while the reciprocal Markov models are used for destination prediction. Towards this goal, Bayesian signal processing algorithms with polynomial complexity are also presented. The versatility of such models is illustrated with tracking applications in radar-based and optical surveillance.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Mohammadi, Farid. "A Meta-Analysis on Solar Cell Technologies." Thesis, Mittuniversitetet, Avdelningen för elektronikkonstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-32584.
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The objective of this study is analysing the characteristics of five different solar cell technologies regarding their efficiency, fill factor, cost and environmental impacts and comparing their improvement records over years considering their efficiency. The five solar cell technologies of interest are amorphous silicon, monocrystalline silicon, polycrystalline silicon, cupper indium gallium selenide thin film and cadmium telluride thin film. The structure and manufacturing process of each of cell technologies were discussed. The study was conducted by the aid of available scientific reports regarding the electrical characteristics of different solar cell technologies. The extracted information regarding efficiency rate and fill factor was analysed using graphs and significant findings are discussed. The five technologies are also compared regarding their cost and ease of fabrication and their impacts on environment and recycling challenges. The result of this study is suggesting the most promising technology that may be the optimal option for further investment and research.
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Luo, Dehui. "Statistical learning of median in meta-analysis." HKBU Institutional Repository, 2017. https://repository.hkbu.edu.hk/etd_oa/469.
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As one of the most recommended strategies in decision making of contemporary medicine, evidence-based medicine (EBM) is attracting more and more attention. For EBM, the scientific evidences are obtained mainly from the randomized controlled trials (RCTs), systematic review and meta-analysis. In particular, meta-analysis can help researchers statistically combine several independent studies for a same clinical problem. In meta-analysis, Cohen's d and Hedges' g are among the most commonly used effect size measurements for continuous data. To compute these mean difference criteria, the sample mean and standard deviation are two conventional statistics reported in the literature. However, some other clinical studies may instead report the median, minimum and maximum values, and/or sample quartiles. Such a situation requires researchers to estimate the sample mean and standard deviation from these reported summary statistics. We note, however, that most existing estimators in the literature have some serious limitations. For this, we propose to improve the existing methods and extend them to three frequently encountered scenarios. In this thesis, we developed the optimal sample mean estimators, the normality test statistics and the updated Cohen's d mean difference criterion for three commonly encountered scenarios in meta-analysis. In Chapter 1, we gave a brief introduction on evidence-based medicine, meta-analysis and the summary data. In Chapter 2, we introduced our optimal estimators of the sample mean under the three scenarios, respectively. In Chapter 3, we proposed several methods for testing the normality of the underlying data. And in Chapter 4, we proposed to improve the famous Cohen's d and its relevant parameters. To assess the practical performance of our newly proposed methods, we also chose a few real data at the end of each chapter as illustrating examples. Numerical results of those studies indicated that our proposed methods have satisfactory performance both in theory and in practice. Following our new methodology, we also recommended an improved procedure for medical researchers to conduct meta-analysis. For illustration, we chose a meta-analysis in Chapter 5 on the effect of phytosterols to plasma CRP level (Rocha et al., 2016) to compare the results obtained from our recommended procedure and from the original methods. The results showed that our recommended procedure may lead to distinctly different results for a same clinical problem. To conclude the thesis, we expect that our newly proposed methods can be regarded as "rules of thumb" and will soon be widely applied in meta-analysis and evidence-based medicine.
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Barrowman, Nicholas J. "Nonlinear mixed effects models for meta-analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ57342.pdf.
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Lu, Guobing. "Development of mixed treatment comparison meta-analysis." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627939.
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Mixed treatment comparison (MTC) meta-analysis, or network meta-analysis, is a methodology developed in the last decade for synthesizing both direct and indirect evidence on multiple treatments from randomised controlled trials available in a therapeutic area, while respecting the randomisation of the included trials. As a natural extension of ordinary pairwise comparison meta-analysis, MTC has increasingly been used in medical research and health technology assessment. The eleven papers (PI-PI 1) on MTC meta-analysis included in this thesis were published in peer-viewed journals from 2004 to early 2013, which was a period of rapid growth of this research topic_ These papers have substantially contributed to the development of MTC meta-analysis in both theory and applications_ They are organised into four chapters (Chapters 3-6) according to their roles in the development of MTC rather than the chronological order of publishing, which are the body of the commentary part of this thesis. In each of these chapters, my comments will be focused on the basic idea behind each included paper and its role in developing the MTC methodology_ Treated as a system of methodology on MTC meta-analysis, these included publications are intrinsically related in a connection network (Chapter 7), where three pivotal papers (P 1, P4 and P 11) provided fundamental concepts and models, four extension papers (P7 -PlO) generalised the basic models to more complex situations, and the rest were concerned with practical applications (P2-3) and issues on assessing evidence inconsistency (P5-6). The significance of the included published work on the development of MTC is discussed in the conclusion chapter around several statistical and methodological aspects of evidence synthesis.
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Higgins, Julian P. T. "Exploiting information in random effects meta-analysis." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387704.
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Swinton, Jonathan J. "Adoptees and behavior problems: A meta-analysis." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/13098.
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Doctor of PhilosophyDepartment of Family Studies and Human Services
Jared R. Anderson
Sandra M. Stith
Adoption trends have shifted in the past two decades and as a result, could impact established assumptions about behavior problems among adopted children. A comprehensive meta-analysis was published in 2005 attempting to come to more definitive conclusions regarding adoption behavior and moderators of adoption behavior. However, the study used a sample from over a dozen countries over a 44 year span. This study is a meta-analysis that has replicated many of the questions investigated by the previous analysis with a much more recent 15 year sample of adoptees placed only within the United States. The results show that combined international and domestic adoptee samples, as well as separate international and domestic adoptee samples are more likely to have total, externalizing, and internalizing behavior problems than their non-adopted counterparts. In addition, age at time of assessment, gender of adoptees, and length of time spent with adoptive family may moderate some of the behavior problems experienced by adoptees. Pre-adoptive adversity, age at time of assessment, and study quality were not shown to have moderating influence on behavior of adoptees.
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Henderson, Elena Kelsey. "Cross-Group Relationship Satisfaction: A Meta-Analysis." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/8477.
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Cross-group relationships are defined by romantic relationships involving two individuals from distinct racial or ethnic groups. For this paper, the terms “interethnic” and “interracial” are used as specifiers for the umbrella terms, “intergroup” and “cross-group.” Studies examining whether cross-group romantic relationships are more or less satisfying than intergroup romantic relationships have yielded discrepant findings. Through a systematic review and meta-analysis of 27 studies, we found that there are no significant difference between cross-group and intergroup relationship satisfaction (aggregate d = .024, 95% CI [-0.076; 0.123]). Tests of moderation found that the amount of Asian participants included in individual studies on cross-group relationship satisfaction is significantly associated with effect size d (β = .005, p = .02; 95% CI [.001; .008]).
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Richardson, Evelyn Cherita. "Meta-analysis of Student Assistance program Outcomes." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/77282.
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The main purpose of this study was to conduct a meta-analysis with data collected from seven schools in Southwest Virginia school district. Data was collected for students who were referred to the Student Assistance Programs at each school. Tracking forms were used to record data for each student. Each tracking form was completed by the Student Assistance Program coordinators for their respective schools. This research was conducted in order to evaluate measurable performance outcomes of Student Assistance Programs. The results highlight the positive effects that Student Assistance Programs, SAP members, and other individuals associated with Student Assistance Programs have on students in need. The positive effect from participation in Student Assistance Programs is encouraging. However, recommendations are made for future research and implications of the current research are discussed. The need for additional research on this topic is prominent throughout this document.Ph. D.
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Hanson, Aubree. "SELF-MONITORING FOR ADHD: A META-ANALYSIS." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1530627826187335.
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Nakanishi, Takayuki. "A Meta-Analysis of Extensive Reading Research." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/245857.
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CITE/Language ArtsEd.D.
The purpose of this study is to investigate the overall effectiveness of extensive reading, and whether learners' ages impact learning from extensive reading differently. The second purpose is to investigate whether the length of time that second language learners engaged in extensive reading influenced outcome measures, and if an effect is found, identify effective periods of time for learners to engage in extensive reading. Meta-analysis was used to investigate the trends shown by past empirical research, chart future research directions, and provide a means to create alternative hypotheses for future research. Two types of empirical studies were conducted: group contrasts of studies that included control groups and pre-post contrasts of studies that only include experimental groups. This meta-analysis included 34 studies that provided 43 unique effect sizes (22 effect sizes for group contrasts and 21 effect sizes for pre-post contrasts) and a total sample size of 3,942 participants. Students who received extensive reading instruction outperformed those who did not. The effect size was small for group contrasts (d = .46) and medium for pre-post contrasts (d = .71). Moderator variables for each contrast were examined to assess the impact of learners' ages and the length of instruction; however, all groups substantially overlapped with each other in terms of their confidence intervals, indicating no statistically significant difference among the groups. There was a small effect size for university students for the group contrast (d = .48), a medium effect for high school students (d = .61), a large effect for university students (d = 1.12), and a large effect for adults (d = 1.48) for pre-post contrasts. In terms of the length of instruction, both one semester of instruction (d = .36) and one year of instruction (d = .52) produced a small effect for group contrasts, while one year of instruction produced a medium effect (d = .74) for pre-post contrasts. In sum, the available extensive reading research to date suggests that extensive reading improves students' reading proficiency and should therefore be a part of foreign language reading curricula.
Temple University--Theses
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Minte-Vera, Carolina V. "Meta-analysis of density-dependent somatic growth /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/5395.
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Simbrunner, Philipp, and Bodo B. Schlegelmilch. "Moral licensing: a culture-moderated meta-analysis." Springer, 2017. http://dx.doi.org/10.1007/s11301-017-0128-0.
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Moral licensing is a cognitive bias, which enables individuals to behave immorally without threatening their self-image of being a moral person. We investigate this phenomenon in a cross-cultural marketing context. More specifically, this paper addresses the questions (i) how big moral licensing effects typically are and (ii) which factors systematically influence the size of this effect. We approach these questions by conducting a meta-analysis and a meta-regression. Based on a random effects model, the point estimate for the generalized effect size Cohen's d is 0.319 (SE = 0.046; N = 106). Results of a meta-regression advance theory, by showing for the first time that both cultural background and type of comparison explain a substantial amount of the total variation of the effect size of moral licensing. Marketing practitioners wishing to capitalize on moral licensing effects should therefore consider cross-cultural difference, since marketing measures building on this effect may lead to different revenues in different countries.
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Fifer, Sarah. "Meta-Analysis of the Efficacy of Neurofeedback." ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/5858.
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Decreases in overall well-being and daily functioning result from unpleasant and uncomfortable symptoms associated with physical health and mental health disorders. Neurofeedback training, rooted in the theory of operant conditioning, presents the possibility of increasing brain wave regulation, decreasing symptoms experienced from abnormal brain wave activity, and increasing overall well-being and daily functioning. The efficacy of neurofeedback for physical and mental health outcomes is unclear, contributing to confusion about the treatment and any potential benefits. In order to assess the efficacy of neurofeedback in the alleviation of physical health and mental health symptoms, a systematic review and meta-analysis of neurofeedback using a random effects model to generate the effect sizes was conducted on 21 studies with 22 comparisons that used neurofeedback to treat patients. The results showed that neurofeedback can be effective for physical and mental health outcomes, including for autism with an effect size of 0.29, tinnitus with an effect size of 0.77, schizophrenia with an effect size of 0.76, depression with an effect size of 0.28, insomnia with an effect size of 0.52, obesity with an effect size of 0.40, intellectual disability with an effect size of 0.73, and pain with an effect size of 0.30. Well-being and daily functioning for those with physical and mental health disorders can be improved. These findings have implications for clinical practice to help patients in treatment for physical and mental health problems, and also for social change by providing evidence for alternative health care options.
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Moody, Ann Michelle. "A meta-analytic review of the performance-cue bias." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/moody/MoodyA0505.pdf.
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Di, Gessa Giorgio. "Simple strategies for variance uncertainty in meta-analysis." Connect to e-thesis, 2007. http://theses.gla.ac.uk/128/.
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Thesis (M.Sc.(R)) - University of Glasgow, 2007.M.Sc.(R) thesis submitted to the Department of Statistics, Faculty of Information and Mathematical Sciences, University of Glasgow, 2007. Includes bibliographical references. Print version also available.
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Ronco, Sharron L. (Sharron Lee). "Comparison of Methods for Computation and Cumulation of Effect Sizes in Meta-Analysis." Thesis, North Texas State University, 1987. https://digital.library.unt.edu/ark:/67531/metadc331655/.
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This study examined the statistical consequences of employing various methods of computing and cumulating effect sizes in meta-analysis. Six methods of computing effect size, and three techniques for combining study outcomes, were compared. Effect size metrics were calculated with one-group and pooled standardizing denominators, corrected for bias and for unreliability of measurement, and weighted by sample size and by sample variance. Cumulating techniques employed as units of analysis the effect size, the study, and an average study effect. In order to determine whether outcomes might vary with the size of the meta-analysis, mean effect sizes were also compared for two smaller subsets of studies.
An existing meta-analysis of 60 studies examining the effectiveness of computer-based instruction was used as a data base for this investigation. Recomputation of the original study data under the six different effect size formulas showed no significant difference among the metrics. Maintaining the independence of the data by using only one effect size per study, whether a single or averaged effect, produced a higher mean effect size than averaging all effect sizes together, although the difference did not reach statistical significance. The sampling distribution of effect size means approached that of the population of 60 studies for subsets consisting of 40 studies, but not for subsets of 20 studies.
Results of this study indicated that the researcher may choose any of the methods for effect size calculation or cumulation without fear of biasing the outcome of the metaanalysis. If weighted effect sizes are to be used, care must be taken to avoid giving undue influence to studies which may have large sample sizes, but not necessarily be the most meaningful, theoretically representative, or elegantly designed. It is important for the researcher to locate all relevant studies on the topic under investigation, since selective or even random sampling may bias the results of small meta-analyses.
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Oviatt, David P. "Social facilitation and motor performance a meta-analysis /." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2629.
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Thesis (M.A.) -- University of Maryland, College Park, 2005Thesis research directed by: Kinesiology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Fredriksson, Jesper. "Evolutionary Development of Brain Imaging Meta-analysis Systems." Licentiate thesis, KTH, Numerical Analysis and Computer Science, NADA, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1440.
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Cromwell, Bryan. "A Meta-Analysis of Test-Retest Reliability Studies." TopSCHOLAR®, 2005. http://digitalcommons.wku.edu/theses/494.
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The effect of intertest interval on test-retest reliability has received little attention in the research literature. In addition, no information has been gathered regarding the intertest intervals currently being used in test-retest reliability studies. This meta-analysis consists of 172 test-retest reliability studies. We hypothesized that the length of the intertest interval would be negatively associated with the test-retest reliability coefficient. The results of the study show that a median intertest interval of 14 days is typically usedin test-retest reliability studies. Data are also provided on typical intertest intervals and test-retest reliabilities categorized by the type of test and the type of sample used in the study. Of the 172 studies used to gather normative data, 69 studies used sample sizes large enough (minimum N = 100) to be used in the test of our hypothesis. The results show that there is a significant negative correlation, r = -.31, between intertest interval and test-retest reliability. This relationship is linear when used to describe intertest intervals shorter then 90 days, but shows a nonlinear relationship when studies using intertest intervals longer then 90 days are included.
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Van, Stavel Rosemary. "Effects of exercise on stress : a meta-analysis." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30159.
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Physical exercise is frequently prescribed by clinicians and researchers as an effective stress reduction technique. There has been some research to support this assertion, however the research has been varied in its methodological rigor. The design problems, variations in exercise programs, and the use of a wide range of psychological measures have made results difficult to interpret. Additionally, the psychological benefits and underlying change processes have not been clearly delineated. The purpose of this study was to conduct a meta-analysis of the research in this area in an attempt to answer specific questions regarding the role of exercise in stress reduction. This meta-analytic approach was
chosen because it permits the quantitative integration of findings of several studies and consideration of the variables that may influence the variance in study outcomes. The effectiveness of exercise as a treatment for stress, the type of exercise that was most beneficial, and the type of individual who gained the most from the exercise intervention was examined.
The 61 effect sizes, which were calculated from 24 studies included in the meta-analysis, were coded along with other variables considered important. Study components such as design type, stress level, type of exercise program, program length, frequency of exercise sessions, attrition rate, psychological measure, composition of sample, gender, and
study type were coded as independent variables. Effect size
was the dependent variable. Analysis of variance revealed that
exercise was an effective stress reducer, stressed people
gained a greater stress reduction effect than minimally
stressed people, and there were no differences between trait
and state anxiety reduction from pre- to post-exercise
program. In addition, a one-way ANOVA indicated that there was
a significant difference between program lengths. Examination
of the means revealed that an 8- to 12-week program was most
effective in reducing stress. Although there was a greater effect size for unpublished studies than published studies, the pattern of change for each study type was similar.
The significance of these results and recommendations for future studies are discussed.Education, Faculty of
Curriculum and Pedagogy (EDCP), Department of
Graduate
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Simmonds, Mark Crawford. "Statistical methods for individual patient data meta-analysis." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595824.
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McAuley, Laura M. "The influence of 'grey' literature on meta-analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ46592.pdf.
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