Semi-natural grasslands are species-rich and one of the most threatened habitats in Europe, since land-use changes have led to reduced area of grassland. Appropriate management practices like grazing or mowing is needed to maintain the conservation values and species-richness of semi-natural grasslands. However, few studies have investigated which of grazing or mowing is most appropriate. Furthermore, almost no studies have investigated which mowing technique is best for the conservation value of grassland flora. The aim of this study was to determine which management practice of grazing and mowing, and which mowing technique, has the most positive effect on grassland flora. Data from two long-term trials were evaluated: one compared the effect of grazing and mowing in eleven sites in southern Sweden during at least twelve years; the other compared the effect of the knife mower and grass trimmer at different cutting heights in one site during twelve years. Meta-analysis was used, based on the odds for a plant record being an indicator species, using eight different indicator systems of classification of grassland plants. Over time, results show increasing odds of finding indicators of good management and no change in odds of finding indicators of lack of management in mowed compared to grazed plots. There were no differences in the odds of finding any indicator species for any of the mowing techniques. Hence, to maintain the conservation values of semi-natural grasslands, mowing is the better management practice compared to grazing. Mowing using a knife mower or grass trimmer has similar effects, and can both be recommended.

De acuerdo con la literatura científica, la frecuencia del acortamiento de los isquiotibiales, está relacionado con factores genéticos, hábitos diarios y actividades deportivas. Sin embargo, con las numerosas metodologías de tratamiento propuestas en la literatura se hace difícil establecer cuál de ellas resulta ser la más efectiva. En este trabajo se llevó a cabo meta-análisis sobre la eficacia de los tratamientos para la ganancia de flexibilidad en los músculos isquiotibiales. La búsqueda de la literatura permitió identificar 41 estudios, 39 publicados y 2 no publicados, entre 1930 y 2007, que cumplieron con los criterios de inclusión, totalizando 85 comparaciones entre grupo tratado y control. El índice del tamaño del efecto utilizado fue la diferencia de medias estandarizada. Los tratamientos obtuvieron una efectividad estadísticamente significativa (d+ = 1,054). El estiramiento muscular, más la combinación de estiramiento más calentamiento resultaron ser los tratamientos más efectivos. La relación entre el tamaño del efecto con las demás variables de tratamiento, de sujeto, metodológicas y extrínsecas, también fueron examinadas. El sesgo de publicación no fue una amenaza contra la validez de los resultados. Los tratamientos son más eficaces cuando: son empleados en sujetos del género femenino; cuanto más jóvenes sean los sujetos; y cuando se utiliza un número mayor de semanas de tratamiento. / According to the scientific literature, the frequency of the shortened hamstring, is related to genetic factors, daily habits and sports activities. In spite of the found treatment methodologies diversity is difficult to establish which of them is more effective. In this paper we carried out a meta-analysis about the efficacy of the treatment for the increase the flexibility in the hamstring muscle. The searched of the literature enabled us identify 41 studies, 39 published and 2 no published, between 1930 and 2007, that fulfilled our the selection criteria, giving a total 85 comparisons between a treated an a control group. The effect size index was the standardized mean difference in the posttest. The treatments obtained a statistically significant effectiveness (d+ = 1,054). The stretching and stretching plus warming -up resulted to be the treatment more effective. The relationship of others treatment, subjects, methodological and extrinsic variables with the effect size were also examined. The publication bias was not a threat against the validity of the results. The treatments are more efficient when: they are applied in subjects of the feminine gender; the more young be the subjects and when a greater number of weeks of treatment are utilized

To understand the etiology of psychopathic personality traits and thus in the long run to be able to develop successful prevention, a first step is to find out what role genetic and environmental effects play. A meta-review of 15 twin studies (N=26, 981), was conducted to estimate the magnitude of genetic and environmental influences on psychopathic personality traits. The results show that additive genetic (heritable) factors and non-shared environmental factors each explain 50% of the variance in psychopathic personality traits, while shared environmental factors were of no importance. Measure, informant, age, and sex were investigated as potential moderators showing that informant had an impact on the findings. This meta-analysis provides a structured synthesis of the relative genetic and environmental contributions in psychopathic personality traits through various stages of development and across sex. / För att förstå etiologin av psykopatiska personlighetsdrag och därmed i det långa loppet kunna utveckla framgångsrik prevention, är ett första steg att klargöra vilken roll genetiska och miljömässiga effekter spelar. En meta-översikt på 15 tvillingstudier (N=26,981), genomfördes för att uppskatta i vilken grad genetiska och miljömässiga faktorer påverkar psykopatiska personlighetsdrag. Resultaten visade att additiva genetiska (ärftliga) och unika miljömässiga faktorer förklarar 50% var av variansen i psykopatiska personlighetsdrag, medan delade miljömässiga faktorer inte var av betydelse. Mått, informant, ålder och kön undersöktes som potentiella moderatorer och visade att informant påverkade resultaten. Denna meta-analys ger en strukturerad syntes av de relativa genetiska och miljömässiga bidrag som påverkar psykopatiska personlighetsdrag genom olika utvecklingsstadier och mellan könen.

We are concerned with testing for differential expression and consider three different aspects of such testing procedures. First, we develop an exact ANOVA type model for discrete gene expression data, produced by technologies such as a Massively Parallel Signature Sequencing (MPSS), Serial Analysis of Gene Expression (SAGE) or other next generation sequencing technologies. We adopt two Bayesian hierarchical models—one parametric and the other semiparametric with a Dirichlet process prior that has the ability to borrow strength across related signatures, where a signature is a specific arrangement of the nucleotides. We utilize the discreteness of the Dirichlet process prior to cluster signatures that exhibit similar differential expression profiles. Tests for differential expression are carried out using non-parametric approaches, while controlling the false discovery rate. Next, we consider ways to combine expression data from different studies, possibly produced by different technologies resulting in mixed type responses, such as Microarrays and MPSS. Depending on the technology, the expression data can be continuous or discrete and can have different technology dependent noise characteristics. Adding to the difficulty, genes can have an arbitrary correlation structure both within and across studies. Performing several hypothesis tests for differential expression could also lead to false discoveries. We propose to address all the above challenges using a Hierarchical Dirichlet process with a spike-and-slab base prior on the random effects, while smoothing splines model the unknown link functions that map different technology dependent manifestations to latent processes upon which inference is based. Finally, we propose an algorithm for controlling different error measures in a Bayesian multiple testing under generic loss functions, including the widely used uniform loss function. We do not make any specific assumptions about the underlying probability model but require that indicator variables for the individual hypotheses are available as a component of the inference. Given this information, we recast multiple hypothesis testing as a combinatorial optimization problem and in particular, the 0-1 knapsack problem which can be solved efficiently using a variety of algorithms, both approximate and exact in nature.

Teams are pervasive in organizations and provide an important contribution to organizational productivity. Since Hackman's (1987) seminal work, the team research focus has shifted from describing teams to outlining how researchers might use points of leverage, such as team design, to increase team effectiveness. There has been a wealth of research on team design variables that relate to team effectiveness. However, more than 15 years later, the team design literature remains fragmented and is inconsistent, and conclusions regarding optimal team design are difficult to make. The present study sought to unify the team design research by proposing a conceptual model and testing hypothesized relationships between specified design variables and team effectiveness using meta-analytic techniques. Specifically, the objectives of this study were to: (a) identify team design variables over which researchers and practitioners have some degree of control, (b) summarize the literature related to each of these variables, (c) hypothesize how each of the design variables are related to team effectiveness, (d) assess the relationship between these variables and team effectiveness using meta-analysis, (e) assess the influence of specified moderator variables (e.g., study setting, team tenure) on the team design variable/team effectiveness relationships, (f) make theoretically- and empirically-based recommendations for the design of effective teams, and (g) highlight areas in need of additional research. Results indicated that several team design variables show promise as a means of increasing team effectiveness. The strength of the team composition variable/team performance relationships was dependent on the study setting (lab or field); however, the study setting had considerable overlap with the type of team assessed (intellectual or physical). For lab studies (intellectual teams), team general mental ability (GMA) and task-relevant expertise were strong predictors of team performance, while team personality variables were unrelated to team performance. In field studies (physical teams), team agreeableness and conscientiousness had stronger relationships with team performance than team GMA and team task-relevant expertise. Team task design variables (e.g., task significance) had consistent, positive relationships with team performance, and several team structure variables (e.g., degree of self- management) were also related to team performance.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 134 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Validity generalization work over the past 25 years has called into question the veracity of the assumption that validity is situationally specific. Recent theoretical and methodological work has suggested that validity coefficients may be transportable even if true validity is not a constant. Most transportability work is based on the assumption that the distribution of rho ( ) is normal, yet, no empirical evidence exists to support this assumption. The present study used a competing model approach in which a new procedure for assessing transportability was compared with two more commonly used methods. Empirical Bayes estimation (Brannick, 2001; Brannick & Hall, 2003) was evaluated alongside both the Schmidt-Hunter multiplicative model (Hunter & Schmidt, 1990) and a corrected Hedges-Vevea (see Hall & Brannick, 2002; Hedges & Vevea, 1998) model. The purpose of the present study was two-fold. The first part of the study compared the accuracy of estimates of the mean, standard deviation, and the lower bound of 90 and 99 percent credibility intervals computed from the three different methods across 32 simulated conditions. The mean, variance, and shape of the distribution varied across the simulated conditions. The second part of the study involved comparing results of analyses of the three methods based on previously published validity coefficients. The second part of the study was used to show whether choice of method for determining whether transportability is warranted matters in practice. Results of the simulation analyses suggest that the Schmidt-Hunter method is superior to the other methods even when the distribution of true validity parameters violates the assumption of normality. Results of analyses conducted on real data show trends consistent with those evident in the analyses of the simulated data. Conclusions regarding transportability, however, did not change as a function of method used for any of the real data sets. Limitations of the present study as well as recommendations for practice and future research are provided. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

The purpose of this meta-analysis was to examine the effect of situated learning on the academic performance of students with and without disabilities in inclusive general education classrooms. While previous research has reported the overall effectiveness of situated learning, relatively few studies have been conducted to investigate how situated learning influences students' academic performances in inclusive settings where students with and without disabilities work together. Moreover, although the main interest of situated learning is about how to apply basic knowledge and skills to an authentic context and, beyond this, how to transfer them into a similar but novel situation in everyday life, little has been known about its effectiveness on students' achievement in terms of knowledge transfer. In this study, a meta-analytical statistical method was employed to investigate the effect of situated learning, and its effectiveness was examined according to the three levels of knowledge transfer (knowledge acquisition, application, and transfer). A total of 19 situated-learning studies, both published and unpublished, were analyzed. Each primary study's effect sizes were calculated using Hedges' g with the bias correction and then combined into the three weighted average effect sizes regarding the levels of knowledge transfer. This meta-analytic study found that, on all of the levels of knowledge transfer, the situated learning is effective for the learning of students with and without disabilities in inclusive general education classrooms. In the random effects model, the situated instruction produced a weighted mean effect size estimate of 2.049 for knowledge acquisition, 1.836 for knowledge application, 1.185 for knowledge transfer. In addition, the percentage of students with special needs in general education classrooms had a negative influence on the effectiveness of situated learning. However, the pattern of results also showed that the proportion of students with special needs in general education classrooms does not influence as greatly the learning of knowledge transfer as it does knowledge acquisition or application. / text

Because both validity and reliability indices are a function of the scores on a given administration of a measure, their values can often vary across samples. It is a common mistake to say that a test is reliable when in fact it is not the test that is reliable but the scores on the test that are reliable. In 1998, vacha-haase proposed a fixed-effects meta-analytic method for evaluating reliability that is similar to validity generalization studies called reliability generalization (rg). This study was conducted to evaluate alternative analysis strategies for the meta-analysis method of reliability generalization when the reliability estimates are not statistically independent. Five approaches for handling the violation of independence were implemented: ignoring the violation and treating each observation as independent, calculating one mean or median from each study, randomly selecting only one observation per study, or using a mixed effects model. This Monte Carlo study included five factors in the method. These factors were (a) the coefficient alpha, (b) sample size in the primary studies, (c) number of primary studies in the rg study, (d) number of reliability estimates from each, and (e) the degree of violation of independence where the strength of the dependence is related to the number of reliability indices (i.e. coefficient alpha) derived from a simulated set of examines and the magnitude of the correlation between the journal studies (with intra-class correlation icc = 0, .0l , .30, and .90). These factors were used to simulate samples under known and controlled population conditions. In general, the results suggested that the type of treatment does not have a noticeable impact on the accuracy of the reliability results but that researchers should be cautious when the intra-class correlation is relatively large. In addition, the simulations in this study resulted in very poor confidence band coverage. This research suggested that RG meta-analysis methods are appropriate for describing the overall average reliability of a measure or construct but the RG researcher should be careful in regards to the construction of confidence intervals.

Since Bowlby (1958, cited in Bowlby, 1969) originally introduced the theory of attachment it has been written about extensively and a vast amount of research has contributed to the development of the theory. In more recent years research has focused on the possible link between attachment and psychopathology. The major aim of the present meta-analysis was to contribute to this research effort by establishing the magnitude of the effect size for the relationship between attachment security and internalizing psychopathology; and attachment security and externalizing psychopathology, in children and adolescents. Four separate meta-analyses were conducted investigating internalizing and externalizing problems in cross-sectional and prospective studies. A comprehensive literature search was conducted to identify relevant studies for inclusion in the analysis. Identified studies were assessed for eligibility according to stringent inclusion and exclusion criteria. A total of 23 studies contributing 45 effect size correlations, involving 3793 different participants were considered eligible for inclusion. Relevant information was extracted and coded from the studies before the analyses were conducted. For cross-sectional studies the mean effect size correlation for attachment security and internalizing psychopathology was r = -0.24 (k = 14; p <0.01; 95% CI = -0.31, -0.17). For attachment security and externalizing psychopathology the mean effect size was r = -0.28 (k = 16; p <0.01; 95% CI = -0.34, -0.21). In terms of prospective studies the mean effect size correlation for attachment security and internalizing psychopathology was r = -0.17 (k = 8; p = 0.01; 95% CI = -0.28, -0.04); and for externalizing psychopathology it was r = -0.09 (k = 7; p = 0.02; 95% CI = -0.16, -0.01). When attachment security and psychopathology were measured concurrently, there was evidence of a negative association for both internalizing and externalizing psychopathology. Although the magnitude of effect was smaller for prospective studies evidence was also found for the predictive validity of a lower level of attachment security in the development of both internalizing and externalizing psychopathology. Theoretical explanations for these findings are presented and the research and clinical implications are discussed in terms of the limitations of the study.

Central to the goals of public health are obtaining and interpreting timely and relevant information for the benefit of humanity. In this dissertation, we propose methods to monitor and assess the spread HIV in a more rapid manner, as well as to improve decisions regarding patient treatment options. In Chapter 1, we propose a method, extending the previously proposed dual-testing algorithm and augmented cross-sectional design, for estimating the HIV incidence rate in a particular community. Compared to existing methods, our proposed estimator allows for shorter follow-up time and does not require estimation of the mean window period, a crucial, but often unknown, parameter. The estimator performs well in a wide range of simulation settings. We discuss when this estimator would be expected to perform well and offer design considerations for the implementation of such a study. Chapters 2 and 3 are concerned with obtaining a more complete understanding of the impact of treatment in randomized clinical trials in which multiple patient outcomes are recorded. Chapter 2 provides an illustration of methods that may be used to address concerns of both risk-benefit analysis and personalized medicine simultaneously, with a goal of successfully identifying patients who will be ideal candidates for future treatment. Riskbenefit analysis is intended to address the multivariate nature of patient outcomes, while “personalized medicine” is concerned with patient heterogeneity, both of which complicate the determination of a treatment’s usefulness. A third complicating factor is the duration of treatment use. Chapter 3 features proposed methods for assessing the impact of treatment as a function of time, as well as methods for summarizing the impact of treatment across a range of follow-up times. Chapter 4 addresses the issue of meta-analysis, a commonly used tool for combining information for multiple independent studies, primarily for the purpose of answering a clinical question not suitably addressed by any one single study. This approach has proven highly useful and attractive in recent years, but often relies on parametric assumptions that cannot be verified. We propose a non-parametric approach to meta-analysis, valid in a wider range of scenarios, minimizing concerns over compromised validity.