Tuesday, January 28, 2014

Introduction to Meta-Analysis


Introduction to Meta-Analysis [Hardcover]

Author: Larry V. Hedges | Language: English | ISBN: 0470057246 | Format: PDF, EPUB

Introduction to Meta-Analysis
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This book provides a clear and thorough introduction to meta-analysis, the process of synthesizing data from a series of separate studies. Meta-analysis has become a critically important tool in fields as diverse as medicine, pharmacology, epidemiology, education, psychology, business, and ecology. Introduction to Meta-Analysis:
  • Outlines the role of meta-analysis in the research process
  • Shows how to compute effects sizes and treatment effects
  • Explains the fixed-effect and random-effects models for synthesizing data
  • Demonstrates how to assess and interpret variation in effect size across studies
  • Clarifies concepts using text and figures, followed by formulas and examples
  • Explains how to avoid common mistakes in meta-analysis
  • Discusses controversies in meta-analysis
  • Features a web site with additional material and exercises

A superb combination of lucid prose and informative graphics, written by four of the world’sleading experts on all aspects of meta-analysis. Borenstein, Hedges, Higgins, and Rothsteinprovide a refreshing departure from cookbook approaches with their clear explanations ofthe what and why of meta-analysis. The book is ideal as a course textbook or for self-study.My students, who used pre-publication versions of some of the chapters, raved about theclarity of the explanations and examples. David Rindskopf, Distinguished Professor of Educational Psychology, City University of New York, Graduate School and University Center, & Editor of the Journal of Educational and Behavioral Statistics.

The approach taken by Introduction to Meta-analysis is intended to be primarily conceptual,and it is amazingly successful at achieving that goal. The reader can comfortably skip theformulas and still understand their application and underlying motivation. For the morestatistically sophisticated reader, the relevant formulas and worked examples provide a superbpractical guide to performing a meta-analysis. The book provides an eclectic mix of examplesfrom education, social science, biomedical studies, and even ecology. For anyone consideringleading a course in meta-analysis, or pursuing self-directed study, Introduction toMeta-analysis would be a clear first choice. Jesse A. Berlin, ScD 

Introduction to Meta-Analysis is an excellent resource for novices and experts alike. The bookprovides a clear and comprehensive presentation of all basic and most advanced approachesto meta-analysis. This book will be referenced for decades. Michael A. McDaniel, Professor of Human Resources and Organizational Behavior, Virginia Commonwealth University

Download latest books on mediafire and other links compilation Introduction to Meta-Analysis
  • Hardcover: 452 pages
  • Publisher: Wiley; 1 edition (April 27, 2009)
  • Language: English
  • ISBN-10: 0470057246
  • ISBN-13: 978-0470057247
  • Product Dimensions: 10 x 7 x 1.2 inches
  • Shipping Weight: 2.1 pounds (View shipping rates and policies)
  • Amazon Best Sellers Rank: #120,836 in Books (See Top 100 in Books)
    • #29 in Books > Textbooks > Medicine & Health Sciences > Research > Biostatistics
    • #47 in Books > Medical Books > Basic Sciences > Biostatistics
List of Figures


List of Tables


Acknowledgements


Preface


PART 1: INTRODUCTION


1 HOW A META-ANALYSIS WORKS


Introduction


Individual studies


The summary effect


Heterogeneity of effect sizes


Summary points


2 WHY PERFORM A META-ANALYSIS


Introduction


The SKIV meta-analysis


Statistical significance


Clinical importance of the effect


Consistency of effects


Summary points


PART 2: EFFECT SIZE AND PRECISION


3 OVERVIEW


Treatment effects and effect sizes


Parameters and estimates


Outline


4 EFFECT SIZES BASED ON MEANS


Introduction


Raw (unstandardized) mean difference D


Standardized mean difference, D and G


Response ratios


Summary points


5 EFFECT SIZES BASED ON BINARY DATA (2×2 TABLES)


Introduction


Risk ratio


Odds ratio


Risk difference


Choosing an effect size index


Summary points


6 EFFECT SIZES BASED ON CORRELATIONS


Introduction


Computing R


Other approaches


Summary points


7 CONVERTING AMONG EFFECT SIZES


Introduction


Converting from the log odds ratio to D


Converting from D to the log odds ratio


Converting from R to D


Converting from D to R


Summary points


8 FACTORS THAT AFFECT PRECISION


Introduction


Factors that affect precision


Sample size


Study design


Summary points


9 CONCLUDING REMARKS


Further reading


PART 3: FIXED-EFFECT VERSUS RANDOM-EFFECTS MODELS


10 OVERVIEW


Introduction


Nomenclature


11 FIXED-EFFECT MODEL


Introduction


The true effect size


Impact of sampling error


Performing a fixed-effect meta-analysis


Summary points


12 RANDOM-EFFECTS MODEL


Introduction


The true effect sizes


Impact of sampling error


Performing a random-effects meta-analysis


Summary points


13 FIXED EFFECT VERSUS RANDOM-EFFECTS MODELS


Introduction


Definition of a summary effect


Estimating the summary effect


Extreme effect size in large study


Confidence interval


The null hypothesis


Which model should we use?


Model should not be based on the test for heterogeneity


Concluding remarks


Summary points


14 WORKED EXAMPLES (PART 1)


Introduction


Worked example for continuous data (Part 1)


Worked example for binary data (Part 1)


Worked example for correlational data (Part 1)


Summary points


PART 4: HETEROGENEITY


15 OVERVIEW


Introduction


16 IDENTIFYING AND QUANTIFYING HETEROGENEITY


Introduction


Isolating the variation in true effects


Computing Q


Estimating tau-squared


The I 2 statistic


Comparing the measures of heterogeneity


Confidence intervals for T 2


Confidence intervals (or uncertainty intervals) for I 2


Summary points


17 PREDICTION INTERVALS


Introduction


Prediction intervals in primary studies


Prediction intervals in meta-analysis


Confidence intervals and prediction intervals


Comparing the confidence interval with the prediction interval


Summary points


18 WORKED EXAMPLES (PART 2)


Introduction


Worked example for continuous data (Part 2)


Worked example for binary data (Part 2)


Worked example for correlational data (Part 2)


Summary points


19 SUBGROUP ANALYSES


Introduction


Fixed-effect model within subgroups


Computational models


Random effects with separate estimates of T 2


Random effects with pooled estimate of T 2


The proportion of variance explained


Mixed-effect model


Obtaining an overall effect in the presence of subgroups


Summary points


20 META-REGRESSION


Introduction


Fixed-effect model


Fixed or random effects for unexplained heterogeneity


Random-effects model


Statistical power for regression


Summary points


21 NOTES ON SUBGROUP ANALYSES AND META-REGRESSION


Introduction


Computational model


Multiple comparisons


Software


Analysis of subgroups and regression are observational


Statistical power for subgroup analyses and meta-regression


Summary points


PART 5: COMPLEX DATA STRUCTURES


22 OVERVIEW


23 INDEPENDENT SUBGROUPS WITHIN A STUDY


Introduction


Combining across subgroups


Comparing subgroups


Summary points


24 MULTIPLE OUTCOMES OR TIME POINTS WITHIN A STUDY


Introduction


Combining across outcomes or time-points


Comparing outcomes or time-points within a study


Summary points


25 MULTIPLE COMPARISONS WITHIN A STUDY


Introduction


Combining across multiple comparisons within a study


Differences between treatments


Summary points


26 NOTES ON COMPLEX DATA STRUCTURES


Introduction


Combined effect


Differences in effect


PART 6: OTHER ISSUES


27 OVERVIEW


28 VOTE COUNTING – A NEW NAME FOR AN OLD PROBLEM


Introduction


Why vote counting is wrong


Vote-counting is a pervasive problem


Summary points


29 POWER ANALYSIS FOR META-ANALYSIS


Introduction


A conceptual approach


In context


When to use power analysis


Planning for precision rather than for power


Power analysis in primary studies


Power analysis for meta-analysis


Power analysis for a test of homogeneity


Summary points


30 PUBLICATION BIAS


Introduction


The problem of missing studies


Methods for addressing bias


Illustrative example


The model


Getting a sense of the data


Is the entire effect an artifact of bias


How much of an impact might the bias have?


Summary of the findings for the illustrative example


Small study effects


Concluding remarks


Summary points


PART 7: ISSUES RELATED TO EFFECT SIZE


31 OVERVIEW


32 EFFECT SIZES RATHER THAN P -VALUES


Introduction


Relationship between p-values and effect sizes


The distinction is important


The p-value is often misinterpreted


Narrative reviews vs. meta-analyses


Summary points


33 SIMPSON’S PARADOX


Introduction


Circumcision and risk of HIV infection


An example of the paradox


Summary points


34 GENERALITY OF THE BASIC INVERSE-VARIANCE METHOD


Introduction


Other effect sizes


Other methods for estimating effect sizes


Individual participant data meta-analyses


Bayesian approaches


Summary points


PART 8: FURTHER METHODS


35 OVERVIEW


36 META-ANALYSIS METHODS BASED ON DIRECTION AND P -VALUES


Introduction


Vote counting


The sign test


Combining p-values


Summary points


37 FURTHER METHODS FOR DICHOTOMOUS DATA


Introduction


Mantel-Haenszel method


One-step (Peto) formula for odds ratio


Summary points


38 PSYCHOMETRIC META-ANALYSIS


Introduction


The attenuating effects of artifacts


Meta-analysis methods


Example of psychometric meta-analysis


Comparison of artifact correction with meta-regression


Sources of information about artifact values


How heterogeneity is assessed


Reporting in psychometric meta-analysis


Concluding remarks


Summary points


PART 9: META-ANALYSIS IN CONTEXT


39 OVERVIEW


40 WHEN DOES IT MAKE SENSE TO PERFORM A META-ANALYSIS?


Introduction


Are the studies similar enough to combine?


Can I combine studies with different designs?


How many studies are enough to carry out a meta-analysis?


Summary points


41 REPORTING THE RESULTS OF A META-ANALYSIS


Introduction


The computational model


Forest plots


Sensitivity analysis


Summary points


42 CUMULATIVE META-ANALYSIS


Introduction


Why perform a cumulative meta-analysis?


Summary points


43 CRITICISMS OF META-ANALYSIS


Introduction


One number cannot summarize a research field


The file drawer problem invalidates meta-analysis


Mixing apples and oranges


Garbage in, garbage out


Important studies are ignored


Meta-analysis can disagree with randomized trials


Meta-analyses are performed poorly


Is a narrative review better?


Concluding remarks


Summary points


PART 10: RESOURCES AND SOFTWARE


44 SOFTWARE


Introduction


Three examples of meta-analysis software


The software


Comprehensive meta-analysis (CMA) 2.0


Revman 5.0


StataTM macros with Stata 10.0


Summary points


45 BOOKS, WEB SITES AND PROFESSIONAL ORGANIZATIONS


Books on systematic review methods


Books on meta-analysis


Web sites


INDEX

Meta-analysis is becoming more and more important in medical research. In my current job I am working on two projects where I am constructing meta-analyses. The pioneering book on this topic was the book by Hedges and Olkin which was the first to put statistical rigor to research synthesis which had previously been done using very ad hoc methods. I have in the past had experience with using published p-values for combination in meta-analysis. It has been more than twenty years since that book came out. You can look a my listmania on meta-analysis to see the various books thyat are currently on the market. Many are theoretical but do not give a good feel for applications. Various approaches have been proposed. There are texts on Bayesian meta-analyse and meta-analyses based on the profile likelihood approach. Some cover p-value combination tests. Some cover special topics such as effect size estimation, mixed modeling approaches.

This book is introductory and is written so clearly that it is useful to research statisticians and novices. Anyone interested in learning about meta-analysis can go to this book and learn a lot from it. Its outstanding features include its organization which divides the text into 10 topicla areas. Each area contains several chapters. Each chapter begins with an introduction and ends with a review of keypoints in bullet form. Key equations are laid out in boxes. The writing is clear and concise. Important concepts are covered first. While the coverage emphasizes methods that combine effect sizes from multiple studies the coverage is very comprehensive and all approaches and issues are touched on or discussed in detail.

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