Larry V Hedges
Datos Biográficos
| ID | 281073 |
|---|---|
| NOMBRE | Larry V Hedges |
| NOMBRES | Larry V |
| APELLIDO | Hedges |
| FIRMA | HEDGES L V |
| AFILIACIONES | University of Chicago |
| ORCID | 0000-0002-7531-0631 |
| VERIFICADO | Sí |
| TOTAL DE OBRAS | 64 |
| TOTAL DE CITAS | 476 |
| TOTAL COMO AUTOR | 63 |
| TOTAL COMO EDITOR | 1 |
| PRIMER AÑO DE PUBLICACIÓN | 1976 |
| AÑO MÁS RECIENTE DE PUBLICACIÓN | 2026 |
| ÍNDICE H | 11 |
Correcting the Variance of Effect Sizes Based on Binary Outcomes for Clustering
Researchers conducting systematic reviews and meta-analyses often encounter studies in which the research design is a well conducted cluster randomized trial, but the statistical analysis does not take clustering into account. For example, the study might assign treatments by clusters but the analysis may not take into account the clustered treatment assignment. Alternatively, the analysis of the primary outcome of the study might take clustering…
Exploring randomised controlled trials in education
Randomised controlled trials (RCTs) are the gold standard for evaluating educational interventions. However, Ireland is approximately 20 years behind the US and 10 years behind the UK in implementing randomised controlled trials in education. This paper examines the role of RCTs in advancing educational research in Ireland, building on a recent commentary by Gilleece and Clerkin (2024. “Towards More Robust Evaluation of Policies and Programmes in…
Interpretation of the Standardized Mean Difference Effect Size When Distributions Are Not Normal or Homoscedastic
The standardized mean difference (sometimes called Cohen’s d) is an effect size measure widely used to describe the outcomes of experiments. It is mathematically natural to describe differences between groups of data that are normally distributed with different means but the same standard deviation. In that context, it can be interpreted as determining several indexes of overlap between the two distributions. If the data are not approximately nor…
ABkPowerCalculator
Single case experimental designs are an important research design in behavioral and medical research. Although there are design standards prescribed by the What Works Clearinghouse for single case experimental designs, these standards do not include statistically derived power computations. Recently we derived the equations for computing power for (AB)k designs. However, these computations and the software code in R may not be accessible to appli…
Introduction to Meta‐Analysis
Exploring treatment impact heterogeneity across sites
Assessing heterogeneity and power in replications of psychological experiments
In this study, we reanalyze recent empirical research on replication from a meta-analytic perspective. We argue that there are different ways to define "replication failure," and that analyses can focus on exploring variation among replication studies or assess whether their results contradict the findings of the original study. We apply this framework to a set of psychological findings that have been replicated and assess the sensitivity of thes…
The Handbook of Research Synthesis and Meta-Analysis
The chapter on stochastically dependent effect sizes by Gleser and Olkin (2009) in The handbook of research synthesis and meta-analysis (2nd ed.) describes. Download Here: tinyurl.com/ohnxrcn When the first edition of The Handbook of Research. In book: Handbook of research methods in social and personality psychology A meta-analysis is literally an analysis of analyses, but conventionally the term.
How to Do a Systematic Review
Systematic reviews are characterized by a methodical and replicable methodology and presentation. They involve a comprehensive search to locate all relevant published and unpublished work on a subject; a systematic integration of search results; and a critique of the extent, nature, and quality of evidence in relation to a particular research question. The best reviews synthesize studies to draw broad theoretical conclusions about what a literatu…
Basics of meta‐analysis
When we speak about heterogeneity in a meta‐analysis, our intent is usually to understand the substantive implications of the heterogeneity. If an intervention yields a mean effect size of 50 points, we want to know if the effect size in different populations varies from 40 to 60, or from 10 to 90, because this speaks to the potential utility of the intervention. While there is a common belief that the I 2 statistic provides this information, it …
Redefine statistical significance
Meta‐Analysis
Meta‐analysis is the use of statistical methods to combine the results of independent research studies. The results of each study are summarized by one or more indices of effect size and a sampling uncertainty (variance) for each effect. Representing study results by effect sizes permits the use of statistical methods to synthesize these results across studies. This essay describes the most frequently used effect sizes and their properties. It de…
Meta-Analysis
Statistical Methods for Meta-Analysis
New evidence about language and cognitive development based on a longitudinal study
We review findings from a four-year longitudinal study of language learning conducted on two samples: a sample of typically developing children whose parents vary substantially in socioeconomic status, and a sample of children with pre- or perinatal brain injury. This design enables us to study language development across a wide range of language learning environments and a wide range of language learners. We videotaped samples of children's and …
The Variance of Intraclass Correlations in Three- and Four-Level Models
Intraclass correlations are used to summarize the variance decomposition in populations with multilevel hierarchical structure. There has recently been considerable interest in estimating intraclass correlations from surveys or designed experiments to provide design parameters for planning future large-scale randomized experiments. The large sample distribution of estimates of the intraclass correlation in two-level situations is well known. Cont…
Sources of variability in children’s language growth
A basic introduction to fixed-effect and random-effects models for meta-analysis
There are two popular statistical models for meta-analysis, the fixed-effect model and the random-effects model. The fact that these two models employ similar sets of formulas to compute statistics, and sometimes yield similar estimates for the various parameters, may lead people to believe that the models are interchangeable. In fact, though, the models represent fundamentally different assumptions about the data. The selection of the appropriat…
Robust variance estimation in meta‐regression with dependent effect size estimates
Conventional meta‐analytic techniques rely on the assumption that effect size estimates from different studies are independent and have sampling distributions with known conditional variances. The independence assumption is violated when studies produce several estimates based on the same individuals or there are clusters of studies that are not independent (such as those carried out by the same investigator or laboratory). This paper provides an…
Introduction to Meta‐Analysis
Effect Sizes in Cluster-Randomized Designs
Multisite research designs involving cluster randomization are becoming increasingly important in educational and behavioral research. Researchers would like to compute effect size indexes based on the standardized mean difference to compare the results of cluster-randomized studies (and corresponding quasi-experiments) with other studies and to combine information across studies in meta-analyses. This article addresses the problem of defining ef…
Intraclass Correlation Values for Planning Group-Randomized Trials in Education
Experiments that assign intact groups to treatment conditions are increasingly common in social research. In educational research, the groups assigned are often schools. The design of group-randomized experiments requires knowledge of the intraclass correlation structure to compute statistical power and sample sizes required to achieve adequate power. This article provides a compilation of intraclass correlation values of academic achievement and…
The varieties of speech to young children
This article examines caregiver speech to young children. The authors obtained several measures of the speech used to children during early language development (14-30 months). For all measures, they found substantial variation across individuals and subgroups. Speech patterns vary with caregiver education, and the differences are maintained over time. While there are distinct levels of complexity for different caregivers, there is a common patte…
Preschool children's mathematical knowledge
This study examined the relation between the amount of mathematical input in the speech of preschool or day-care teachers and the growth of children's conventional mathematical knowledge over the school year. Three main findings emerged. First, there were marked individual differences in children's conventional mathematical knowledge by 4 years of age that were associated with socioeconomic status. Second, there were dramatic differences in the a…
The Power of Statistical Tests for Moderators in Meta-Analysis.
Calculation of the statistical power of statistical tests is important in planning and interpreting the results of research studies, including meta-analyses. It is particularly important in moderator analyses in meta-analysis, which are often used as sensitivity analyses to rule out moderator effects but also may have low statistical power. This article describes how to compute statistical power of both fixed- and mixed-effects moderator tests in…
An Exchange
Research on educational production functions attempts to model the relation between resource inputs and school outcomes such as educational achievement. Over the last decade a series of influential reviews of this literature have suggested that there is no systematic relation between resource inputs and school outcomes when controlling for student characteristics such as socioeconomic status. The inference procedure used in these reviews, vote co…
Redefine statistical significance
Preschool children's mathematical knowledge
This study examined the relation between the amount of mathematical input in the speech of preschool or day-care teachers and the growth of children's conventional mathematical knowledge over the school year. Three main findings emerged. First, there were marked individual differences in children's conventional mathematical knowledge by 4 years of age that were associated with socioeconomic status. Second, there were dramatic differences in the a…
Changes in the Black-White Gap in Achievement Test Scores
Two questions of scholarly and public policy interest concerning the well-documented racial difference in scores on achievement tests are : How much of the racial difference (gap) can be attributed to social-class differences between blacks and whites? and How much has the racial gap changed over the past 30 years? To address these questions, the AA. analyzed evidence from seven probability samples of national populations of adolescents from 1965…
The varieties of speech to young children
This article examines caregiver speech to young children. The authors obtained several measures of the speech used to children during early language development (14-30 months). For all measures, they found substantial variation across individuals and subgroups. Speech patterns vary with caregiver education, and the differences are maintained over time. While there are distinct levels of complexity for different caregivers, there is a common patte…
The Effects of Small Classes on Academic Achievement
The effects of class size on academic achievement have been studied for decades. Although the results of small scale randomized experiments and large-scale econometric studies point to positive effects of small classes, some scholar have seen the evidence as ambiguous. This paper reports analyses of a 4-year, large-scale randomized experiment on the effects of class size, project STAR in Tennessee. Although implementation was not perfect, these a…
Estimation of effect size from a series of independent experiments
Trends in Gender Differences in Academic Achievement from 1960 to 1994
Vote-counting methods in research synthesis
Reviews of research usually rely on counts of the number of times the treatment group mean exceeds the control group mean by an amount that is statistically significant. The treatment is said to have a positive effect if the proportion of such positive significant results is large. This procedure is
New evidence about language and cognitive development based on a longitudinal study
We review findings from a four-year longitudinal study of language learning conducted on two samples: a sample of typically developing children whose parents vary substantially in socioeconomic status, and a sample of children with pre- or perinatal brain injury. This design enables us to study language development across a wide range of language learning environments and a wide range of language learners. We videotaped samples of children's and …
Meta-analysis of screening and diagnostic tests
Money Does Matter Somewhere
First, Hanushek seems to question the validity of meta analysis. We, and many other scientists and statisticians, disagree. For example, a recent report of a committee of the Mathematical Sciences Board of the National Research Council (1992), studying problems of combining information in the empirical sciences, concluded that quantitative synthesis—meta-analysis—has gained increasing use in recent years and rightly so. Meta-analysis offers a pow…
The Effects of Class Size
There has recently been a great deal of interest in the use of meta-analysis to integrate research findings. Glass and Smith used meta-analytic techniques to describe the relationship between class size and academic achievement or classroom processes. The statistical methods used by Glass and Smith are open to criticism on several grounds. The present paper reports the results of reanalyses using statistical methods that can be rigorously justifi…
A random effects model for effect sizes
This chapter presents an analogue to random effects analysis of variance for effect size analyses. This model assumes that the population values of the effect size are samples from a distribution of effect size parameters. Thus, the observed variability in sample estimates of effect size is partly because of the variability in the underlying population parameters and partly because of the sampling error of the estimator about the parameter value.…
Clustering estimates of effect magnitude from independent studies
Do the Disadvantaged Benefit More from Small Classes? Evidence from the Tennessee Class Size Experiment
The effects of class size on academic achievement have been studied for decades. Although recent research from randomized experiments points to positive effects of small classes, the evidence about the social distribution of effects is less clear. Some scholars have contended that the effects of small classes are larger for minorities and the disadvantaged. These claims have led to policy decisions to implement small classes to reduce inequality …
Assessing heterogeneity and power in replications of psychological experiments
In this study, we reanalyze recent empirical research on replication from a meta-analytic perspective. We argue that there are different ways to define "replication failure," and that analyses can focus on exploring variation among replication studies or assess whether their results contradict the findings of the original study. We apply this framework to a set of psychological findings that have been replicated and assess the sensitivity of thes…
An Exchange
Who Are America's Gifted
Mainstream education research has devoted little attention to studying highly talented students. Though there exists an expansive specialized literature dedicated to the study of academic giftedness, no recent study has used a large, nationally representative sample to describe gifted American students and how they differ from their nongifted counterparts. Yet identification and management of intellectual talent is essential to maintaining high n…
Nonparametric estimators of effect size in meta-analysis
An Attempt to Improve Prediction of College Success of Minority Students by Adjusting for High School Characteristics
A validity study was conducted to determine whether the addition of a high school rating factor would increase the predictivity of freshman grade point average (GPA) for Educational Opportunity Program (EOP) students at the University of California, San Diego (UCSD). The rating factor for each high school was the mean difference between the high school GPA and the UC freshman GPA of the previous year's graduates from the same high school who atte…
Vote-counting methods in research synthesis
Reviews of research usually rely on counts of the number of times the treatment group mean exceeds the control group mean by an amount that is statistically significant. The treatment is said to have a positive effect if the proportion of such positive significant results is large. This procedure is
Distribution Theory for Glass's Estimator of Effect Size and Related Estimators
Distribution Theory for Glass's Estimator of Effect size and Related Estimators
Glass's estimator of effect size, the sample mean difference divided by the sample standard deviation, is studied in the context of an explicit statistical model. The exact distribution of Glass's estimator is obtained and the estimator is shown to have a small sample bias. The minimum variance unbiased estimator is obtained and shown to have uniformly smaller variance than Glass's (biased) estimator. Measurement error is shown to attenuate estim…
The Influence of Direct Instruction on Student Self-appraisals
The study analyzed student self-appraisal data from an instructional experiment in the third grade. Treatment and aptitude-treatment interaction (ATI) effects were assessed on self-esteem, attitude, anxiety, and locus of control Analyses were performed at the student and class levels to accommodate the hierarchical character of the data. Results showed the instruction favorably influenced self-esteem, attitude, and anxiety. In particular, parent …
Estimation and testing for differences in effect size
Estimation and testing for differences in effect size
Estimation of effect size from a series of independent experiments
Clustering estimates of effect magnitude from independent studies
The Effects of Class Size
There has recently been a great deal of interest in the use of meta-analysis to integrate research findings. Glass and Smith used meta-analytic techniques to describe the relationship between class size and academic achievement or classroom processes. The statistical methods used by Glass and Smith are open to criticism on several grounds. The present paper reports the results of reanalyses using statistical methods that can be rigorously justifi…
Clustering estimates of effect magnitude from independent studies
A random effects model for effect sizes
This chapter presents an analogue to random effects analysis of variance for effect size analyses. This model assumes that the population values of the effect size are samples from a distribution of effect size parameters. Thus, the observed variability in sample estimates of effect size is partly because of the variability in the underlying population parameters and partly because of the sampling error of the estimator about the parameter value.…
Nonparametric estimators of effect size in meta-analysis
Estimation of a Single Effect Size
Meta Analysis
How hard is hard science, how soft is soft science? The empirical cumulativeness of research
Research results in the social and behavioral sciences are often conceded to be less replicable than research results in the physical sciences.However, direct empirical comparisons of the cumulativeness of research in the social and physical sciences have not been made to date.This article notes the parallels between methods used in the quantitative synthesis of research in the social and in the physical sciences.Essentially identical methods are…
How hard is hard science, how soft is soft science? The empirical cumulativeness of research
quot; Research results in the social and behavioral sciences are often conceded to be less replicable than research results in the physical sciences. However, direct empirical comparisons of the cumulativeness of research in the social and physical sciences have not been made to date. This article notes the parallels between methods used in the quantitative synthesis of research in the social and in the physical sciences. Essentially identical me…
Categories and particulars
A model of category effects on reports from memory is presented. The model holds that stimuli are represented at 2 levels of detail: a fine-grain value and a category. When memory is inexact but people must report an exact value, they use estimation processes that combine the remembered stimulus value with category information. The proposed estimation processes include truncation at category boundaries and weighting with a central (prototypic) ca…
Testing the null hypothesis in meta-analysis
Combined significance tests (combined p values) and tests of the weighted mean effect size are both used to combine information across studies in meta-analysis. This article compares a combined significance test (the Stouffer test) with a test based on the weighted mean effect size as tests of the same null hypothesis. The tests are compared analytically in the case in which the within-group variances are known and compared through large-sample t…
Testing the null hypothesis in meta-analysis
Meta-Analysis for Explanation
Meta-Analysis for Explanation
Money Does Matter Somewhere
Money Does Matter Somewhere
First, Hanushek seems to question the validity of meta analysis. We, and many other scientists and statisticians, disagree. For example, a recent report of a committee of the Mathematical Sciences Board of the National Research Council (1992), studying problems of combining information in the empirical sciences, concluded that quantitative synthesis—meta-analysis—has gained increasing use in recent years and rightly so. Meta-analysis offers a pow…
An Exchange
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