scholarly journals Effect sizes and meta-analysis indicate no sex dimorphism in the human or rodent corpus callosum

1998 ◽  
Vol 21 (3) ◽  
pp. 338-339
Author(s):  
Douglas Wahlsten ◽  
Katherine M. Bishop
Keyword(s):  
Standard Deviation ◽  
Corpus Callosum ◽  
Brain Size ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Sex Dimorphism ◽  
Standard Deviations ◽  
Average Size

Sex dimorphism occurs when group means differ by four or more standard deviations. However, the average size of the corpus callosum is greater in males by about one standard deviation in rats, 0.2 standard deviation in humans, and virtually zero in mice. Furthermore, variations in corpus callosum size are related to brain size and are not sex specific.

scholarly journals Evaluation of Joint Position Recognition Measurement Variables Associated With Chronic Ankle Instability: A Meta-Analysis

2012 ◽  
Vol 47 (4) ◽  
pp. 444-456 ◽  
Author(s):  
Jennifer M. Medina McKeon ◽  
Patrick O. McKeon
Keyword(s):  
Ankle Instability ◽  
Meta Analysis ◽  
Plantar Flexion ◽  
Absolute Error ◽  
Chronic Ankle Instability ◽  
Effect Sizes ◽  
Control Group ◽  
Neutral Position ◽  
Joint Position ◽  
Standard Deviations

Objective To identify the most precise and consistent variables using joint repositioning for identifying joint position recognition (JPR) deficits in individuals with chronic ankle instability (CAI). Data Sources We conducted a computerized search of the relevant scientific literature from January 1, 1965, to July 31, 2010, using PubMed Central, CINAHL, MEDLINE, SPORTDiscus, and Web of Science. We also conducted hand searches of all retrieved studies to identify relevant citations. Included studies were written in English, involved human participants, and were published in peer-reviewed journals. Study Selection Studies were included in the analysis if the authors (1) had examined JPR deficits in patients with CAI using active or passive repositioning techniques, (2) had made comparisons with a group or contralateral limb without CAI, and (3) had provided means and standard deviations for the calculation of effect sizes. Data Extraction Studies were selected and coded independently and assessed for quality by the investigators. We evaluated 6 JPR variables: (1) study comparisons, (2) starting foot position, (3) repositioning method, (4) testing range of motion, (5) testing velocity, and (6) data-reduction method. The independent variable was group (CAI, control group or side without CAI). The dependent variable was errors committed during joint repositioning. Means and standard deviations for errors committed were extracted from each included study. Data Synthesis Effect sizes and 95% confidence intervals were calculated to make comparisons across studies. Separate meta-analyses were calculated to determine the most precise and consistent method within each variable. Between-groups comparisons that involved active repositioning starting from a neutral position and moving into plantar flexion or inversion at a rate of less than 5°/s as measured by the mean absolute error committed appeared to be the most sensitive and precise variables for detecting JPR deficits in people with CAI.

A Meta-Analysis on the Effects of Music as Reinforcement for Education/Therapy Objectives

1996 ◽  
Vol 44 (2) ◽  
pp. 105-133 ◽  
Author(s):  
Jayne M. Standley
Keyword(s):  
Subject Matter ◽  
Visual Stimulation ◽  
Meta Analysis ◽  
Social Behaviors ◽  
Effect Sizes ◽  
Baseline Conditions ◽  
Standard Deviations ◽  
Reinforcement Value

This meta-analysis evaluated 208 variables derived from 98 studies incorporating I music as a contingency for education and therapeutic objectives. Variables were converted to effect sizes (ES) via statistical formulae and compared for determination of characteristics affecting reinforcement value of music. The overall benefits attributable to contingent music were almost three standard deviations greater than control/baseline conditions (ES= 2.90). Results demonstrate that contingent music was more effective than contingent nonmusic stimuli used in these studies and more effective than continuous music. Pairing other stimuli such as food, approval, or visual stimulation with the music decreased its effectiveness as a reinforcer. Uniquely, music functioned as a reinforcer and simultaneously as subject matter, and there was evidence of generalized benefit to other academic and social behaviors that were measured but were not contingently reinforced with music.

scholarly journals A Meta-Analysis on the Relationship Between Student Abstinence-Only Programs and Sexual Behavior and Attitudes

2019 ◽  
Vol 52 (1) ◽  
pp. 3-20
Author(s):  
William H. Jeynes
Keyword(s):  
Middle School ◽  
Sexual Behavior ◽  
Standard Deviation ◽  
Significant Relationship ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Standard Deviation Unit ◽  
Premarital Sexual ◽  
The Relationship ◽  
Abstinence Only

This meta-analysis of 14 studies examines the relationship between abstinence-only programs and the sexual behavior and—attitudes of urban students from middle school to early in college. The results indicate a significant relationship between abstinence-only programs and the outcomes examined. Abstinence-only programs, as a whole, were associated with reduced premarital sexual behavior by nearly .4 of a standard deviation unit. For sexual behavior and attitudes combined, abstinence-only programs were associated with improvements of nearly .3 of a standard deviation unit. When sophisticated controls were utilized in each of these analyses, the effect sizes were smaller, but were all statistically significant. The importance of these results is discussed.

scholarly journals Neuroanatomical diversity of corpus callosum and brain volume in the Autism Brain Imaging Data Exchange (Abide) project

2014 ◽  
Author(s):  
Aline Lefebvre ◽  
Anita Beggiato ◽  
Thomas Bourgeron ◽  
Roberto Toro
Keyword(s):  
Corpus Callosum ◽  
Data Exchange ◽  
Brain Volume ◽  
Brain Size ◽  
Intracranial Volume ◽  
Long Distance ◽  
Significant Difference ◽  
Standard Deviations ◽  
Intelligence Scores ◽  
The Brain

The corpus callosum -- the main pathway for long-distance inter-hemispheric integration in the human brain -- has been frequently reported to be smaller among autistic patients compared with non-autistic controls. We conducted a meta-analysis of the literature which suggested a statistically significant difference. However, the studies included were heavily underpowered: on average only 20% power to detect differences of 0.3 standard deviations, which makes it difficult to establish the reality of such a difference. We therefore studied the size of the corpus callosum among 694 subjects (328 patients, 366 controls) from the Abide cohort. Despite having achieved 99% power to detect statistically significant differences of 0.3 standard deviations, we did not observe any. To better understand the neuroanatomical diversity of the corpus callosum, and the possible reasons for the previous findings, we analysed the relationship between its size, the size of the brain, intracranial volume and intelligence scores. The corpus callosum appeared to scale non-linearly with brain size, with large brains having a proportionally smaller corpus callosum. Additionally, intelligence scores correlated with brain volume among controls but the correlation was significantly weaker among patients. We used simulations to determine to which extent these two effects could lead to artefactual differences in corpus callosum size within populations. We observed that, were there a difference in brain volume between cases and controls, normalising corpus callosum size by brain volume would not eliminate the brain volume effect, but adding brain volume as a covariate in a linear model would. Finally, we observed that because of the weaker correlation of intelligence scores and brain volume among patients, matching populations by intelligence scores could result in a bias towards including more patients with large brain volumes, inducing an artificial difference. Overall, our results highlight the necessity for open data sharing efforts such as Abide to provide a more solid ground for the discovery of neuroimaging biomarkers, within the context of the wide human neuroanatomical diversity.

scholarly journals Meta-analysis of the variance ratio

2017 ◽  
Author(s):  
Nicolas Traut
Keyword(s):  
Standard Deviation ◽  
Meta Analysis ◽  
Mean Difference ◽  
Variance Ratio ◽  
Mean Values ◽  
Variance Ratios ◽  
The Mean ◽  
Standard Deviations ◽  
The Difference ◽  
Fisher’S Ratio

IntroductionThe most commonly used effect size when using meta-analysis to compare a measurement of interest in two different populations is the standardised mean difference. This is the mean difference of the measurement divided by the pooled standard deviation in the two groups. The standard deviation is usually supposed to be the same for both groups, although this assumption is often made without any particular evidence. It is possible, however, that the difference of the measurement in the two populations resides precisely in their standard deviations. This could be the case, for example, if a population of patients exhibited more “abnormal” values than a control population – both large and small – even if the mean values were the same. Fisher’s test of equality of variance is designed to compare standard deviations. A variance ratio is a Fisher’s ratio and Fisher distribution can be used to give confidence intervals to the estimate for one study. However, confidence interval for one study can be very wide if the study does not contain enough subjects. Here we present an approach to combine variance ratios of different studies in a meta-analytic way which produces more robust estimates under these circumstances.

The Orchard Plot: Cultivating a Forest Plot for Use in Ecology, Evolution and Beyond

2019 ◽  
Author(s):  
Shinichi Nakagawa ◽  
Malgorzata Lagisz ◽  
Rose E O'Dea ◽  
Joanna Rutkowska ◽  
Yefeng Yang ◽  
...  
Keyword(s):  
Meta Analysis ◽  
R Package ◽  
Effect Sizes ◽  
Forest Plot ◽  
Point Estimates ◽  
Aggregate Effect ◽  
The Individual ◽  
Meta Analyses ◽  
Heterogeneous Effect ◽  
Intuitive Interpretation

‘Classic’ forest plots show the effect sizes from individual studies and the aggregate effect from a meta-analysis. However, in ecology and evolution meta-analyses routinely contain over 100 effect sizes, making the classic forest plot of limited use. We surveyed 102 meta-analyses in ecology and evolution, finding that only 11% use the classic forest plot. Instead, most used a ‘forest-like plot’, showing point estimates (with 95% confidence intervals; CIs) from a series of subgroups or categories in a meta-regression. We propose a modification of the forest-like plot, which we name the ‘orchard plot’. Orchard plots, in addition to showing overall mean effects and CIs from meta-analyses/regressions, also includes 95% prediction intervals (PIs), and the individual effect sizes scaled by their precision. The PI allows the user and reader to see the range in which an effect size from a future study may be expected to fall. The PI, therefore, provides an intuitive interpretation of any heterogeneity in the data. Supplementing the PI, the inclusion of underlying effect sizes also allows the user to see any influential or outlying effect sizes. We showcase the orchard plot with example datasets from ecology and evolution, using the R package, orchard, including several functions for visualizing meta-analytic data using forest-plot derivatives. We consider the orchard plot as a variant on the classic forest plot, cultivated to the needs of meta-analysts in ecology and evolution. Hopefully, the orchard plot will prove fruitful for visualizing large collections of heterogeneous effect sizes regardless of the field of study.

On the sensibility of the Pairs Trading strategy: the case of the FTS stock market index

2020 ◽  
Vol 38 (3) ◽  
Author(s):  
Ainhoa Fernández-Pérez ◽  
María de las Nieves López-García ◽  
José Pedro Ramos Requena
Keyword(s):  
Standard Deviation ◽  
Stock Market ◽  
Trading Strategy ◽  
Stock Market Index ◽  
Pairs Trading ◽  
Empirical Application ◽  
Statistical Arbitrage ◽  
Market Index ◽  
Standard Deviations ◽  
Using Data

In this paper we present a non-conventional statistical arbitrage technique based in varying the number of standard deviations used to carry the trading strategy. We will show how values of 1 and 1,2 in the standard deviation provide better results that the classic strategy of Gatev et al (2006). An empirical application is performance using data of the FST100 index during the period 2010 to June 2019.

Identification of and Correction for Publication Bias: Comment

2019 ◽  
Author(s):  
Amanda Kvarven ◽  
Eirik Strømland ◽  
Magnus Johannesson
Keyword(s):  
Publication Bias ◽  
False Positive ◽  
Large Scale ◽  
Meta Analysis ◽  
False Positive Rate ◽  
Effect Sizes ◽  
Replication Studies ◽  
Moderate Reduction ◽  
Positive Rate ◽  
Meta Analyses

Andrews & Kasy (2019) propose an approach for adjusting effect sizes in meta-analysis for publication bias. We use the Andrews-Kasy estimator to adjust the result of 15 meta-analyses and compare the adjusted results to 15 large-scale multiple labs replication studies estimating the same effects. The pre-registered replications provide precisely estimated effect sizes, which do not suffer from publication bias. The Andrews-Kasy approach leads to a moderate reduction of the inflated effect sizes in the meta-analyses. However, the approach still overestimates effect sizes by a factor of about two or more and has an estimated false positive rate of between 57% and 100%.

Effectiveness of psychological interventions to improve emotion regulation in youth - a meta-analysis

2019 ◽  
Author(s):  
Bettina Moltrecht ◽  
Jessica Deighton ◽  
Praveetha Patalay ◽  
Julian Childs
Keyword(s):  
Emotion Regulation ◽  
Emotion Dysregulation ◽  
Psychological Intervention ◽  
Meta Analysis ◽  
Age Groups ◽  
Effect Sizes ◽  
What Works ◽  
Large Heterogeneity ◽  
Larger Sample

Background: Research investigating the role of emotion regulation (ER) in the development and treatment of psychopathology has increased in recent years. Evidence suggests that an increased focus on ER in treatment can improve existing interventions. Most ER research has neglected young people, therefore the present meta-analysis summarizes the evidence for existing psychosocial intervention and their effectiveness to improve ER in youth. Methods: A systematic review and meta-analysis was conducted according to the PRISMA guidelines. Twenty-one randomized-control-trials (RCTs) assessed changes in ER following a psychological intervention in youth exhibiting various psychopathological symptoms.Results: We found moderate effect sizes for current interventions to decrease emotion dysregulation in youth (g=-.46) and small effect sizes to improve emotion regulation (g=0.36). Significant differences between studies including intervention components, ER measures and populations studied resulted in large heterogeneity. Conclusion: This is the first meta-analysis that summarizes the effectiveness for existing interventions to improve ER in youth. The results suggest that interventions can enhance ER in youth, and that these improvements correlate with improvements in psychopathology. More RCTs including larger sample sizes, different age groups and psychopathologies are needed to increase our understanding of what works for who and when.

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