Larry V. Hedges

Board of Trustees Professor of Statistics and Social Policy,
Faculty Fellow, Institute for Policy Research, Northwestern University
PhD, Mathematical Methods in Educational Research, Stanford University, 1980
l-hedges@northwestern.edu
Curriculum Vitae

A national leader in the fields of educational statistics and evaluation, Larry V. Hedges joined the Northwestern faculty in 2005. He is one of eight Board of Trustees Professors at Northwestern, the university’s most distinguished academic position. He will hold appointments in statistics and education and social policy. Previously, he was the Stella M. Rowley Professor at the University of Chicago.

Hedges’ research straddles many fields—in particular those of sociology, psychology, and educational policy. He is best known for his work to develop statistical methods for meta-analysis (a statistical analysis of the results of multiple studies that combines their findings) in the social, medical, and biological sciences. It is a key component of evidence-based social research. Examples of some his recent studies include: understanding the costs of generating systematic reviews, differences between boys and girls in mental test scores, the black-white gap in achievement test scores, and frameworks for international comparative studies on education.

Widely published, he has authored or co-authored numerous journal articles and five books, including the seminal Statistical Methods for Meta-Analysis: A Practical Guide to Modern Methods of Meta-Analysis (with I. Olkin) and The Handbook of Research Synthesis (with H. Cooper).

He has been elected a member or fellow of numerous boards, associations and professional organizations, including the National Academy of Education, the American Statistical Association, the American Psychological Association, and the Society of Multivariate Experimental Psychology. He is convener of the Campbell Collaboration’s statistics group, which is part of a larger effort to produce an online database of “best practices” in the social sciences and education. He chairs the Technical Advisory Group of the U.S. Department of Education’s What Works Clearinghouse, an initiative to give educators and researchers a library of systematic reviews to aid in the development of evidence-based educational policy.

Current Projects

A Training Institute on Randomized Controlled Trials in Educational Research, funded by the U.S. Institute of Education Sciences. This project provides a series of intensive two-week summer institutes for research professionals who desire advanced training in the design, conduct, and analysis of large scale randomized experiments in education.

The Social Distribution of Academic Achievement in America, funded by the Spencer Foundation. In this project, Hedges and his colleagues seek to document the social distribution of academic achievement in the U.S. By examining various achievement gaps (by gender, race, ethnicity, social class, etc.) in different ways, they come to understand how the social distribution of achievement has changed over the last few decades. A major part of this study evaluates patterns of between- and within-school variability of student achievement. They also examine whether different sources of evidence lead to the same conclusions, that is, they seek to triangulate whenever possible. Finally, the researchers study the—somewhat limited—longitudinal evidence, attempting to coordinate it with repeated cross-sectional evidence. They expect that combining such data may help us understand the emergence of differences in patterns of academic achievement between important population sub-groups. How large, for example, are achievement gaps when students enter school? How do these gaps grow over time? How does social context and school context affect the initial gaps and their growth over time? Do between-school differences grow over time and what is associated with this growth?

A Data Research and Development Center, funded by the National Science Foundation's Interagency Education Research Initiative (IERI). The center’s ongoing research agenda is to develop and apply research methods for identifying educational interventions that can be scaled up without diminishing the effectiveness of these interventions. The work involves basic research on the design and analysis of studies for determining if an intervention has been scaled successfully, and providing technical assistance to IERI projects that are attempting to carry out such studies.

Presentation and Combination of the Results of Multi-site Randomized Experiments in Education, funded by the Institute of Education Sciences (IES). Much of the work on representing the results of experiments via measures of effect size and the combination of these effect sizes across studies has focused on simple, single-site experiments. The recent interest in larger multi-site and group randomized experiments in education requires new methods. This project involves basic research on how to represent the results of multi-site randomized experiments, and how to combine evidence from studies of this type with those from other multi-site randomized trials and from smaller studies.

Selected Publications

Books and Monographs

Hedges, L. V., and B. Schneider, eds. 2005. The Social Organization of Schooling. New York: The Russell Sage Foundation.

Cooper, H. M. and L. V. Hedges, eds. 1994. The Handbook of Research Synthesis. New York: The Russell Sage Foundation.

Draper, D., D. P. Gaver, P. K. Goel, J. B. Greenhouse, L. V. Hedges, C. N. Morris, J. R. Tucker, and C. Waternaux, 1993. Combining Information: Statistical Issues and Opportunities for Research. Washington, D.C.: American Statistical Association.

Cook, T., H. M. Cooper, D. Cordray, L. V. Hedges, R. J. Light, T. Louis, and F. Mosteller. 1991. Meta-Analysis for Explanation. New York: The Russell Sage Foundation.

Hedges, L. V., J. A. Shymansky, and G. Woodworth. 1989. A Practical Guide to Modern Methods of Meta-Analysis. Washington, D.C.: National Science Teachers Association.

Hedges, L. V., and I. Olkin. 1985. Statistical Methods for Meta-Analysis. New York: Academic Press.


Scholarly Articles (selected)

Statistics

Hedges, L. V. (2007). Correcting a significance test for clustering. Journal of Educational and Behavioral Statistics, 32, 151-179.

Hedges, L. V. (2007). Effect sizes in cluster randomized designs. Journal of Educational and Behavioral Statistics, 32, 341-370.

Hedges, L. V. 2007. Meta-analysis. Pages 919-953 in The Handbook of Statistics, ed. C. R. Rao. Amsterdam: Elsevier.

Hedges, L. V., and J. Vevea. 2005. Selection model approaches to publication bias. Pages 145-174 in Publication Bias in Meta-Analysis, ed. H. Rothstein, A. Sutton, and M. Borenstein. New York: John Wiley.

Hedges, L. V., and T. D. Pigott. 2004. The power of statistical tests for moderators in meta-analysis. Psychological Methods 9:426–45.

Hedges, L. V., and T. D. Pigott. 2001. The power of statistical tests in meta-analysis. Psychological Methods 6:203–17.

Educational Policy

Konstantopoulos, S., & Hedges, L. V. (in press). How large an effect can we expect from school reforms? Teacher College Record.

Hedges, L. V. & Hedberg, E. C. (2007). Intraclass correlations for planning group-randomized experiments in education. Educational Evaluation and Policy Aalysis, 29, 60-87.

Nye, B., L. V. Hedges, and S. Konstantopoulos. 2004. How large are teacher effects? Educational Evaluation and Policy Analysis 26:237–57.

Nye, B., L. V. Hedges, and S. Konstantopoulos. 2004. Do minorities experience greater lasting benefits from small classes?: Evidence from a five year followup of the Tennessee class size experiment. Journal of Educational Research 97:94-100.

Hedges, L. V., S. Konstantopoulos, and A. Thoreson. 2003. Studies of technology implementation and effects. In Evaluating educational technology: Effective research designs for improving learning, ed. G. D. Haertel and B. Means, 187–204. New York: Teachers College Press.

Nye, B., L. V. Hedges, and S. Konstantopoulos. 2002. Do low achieving students benefit more from small classes?: Evidence from the Tennessee class size experiment. Educational Evaluation and Policy Analysis 24:201-17.

Nye, B., L. V. Hedges, and S. Konstantopoulos. 2000. The effects of small classes on achievement: The results of the Tennessee class-size experiment. American Educational Research Journal 37:123–51.

Nye, B., L. V. Hedges, and S. Konstantopoulos. 2000. Do minorities and the disadvantaged benefit more from small classes?: Evidence from the Tennessee class-size experiment. American Journal of Education 109:1–26.

Nye, B., L. V. Hedges, and S. Konstantopoulos. 1999. The long-term effects of small classes: A five year follow-up of the Tennessee class-size experiment. Educational Evaluation and Policy Analysis 21:127–42.

Psychology

Huttenlocher, J., Hedges, L. V., Crawford, E., & Corrigan, B. (2007). Estimating stimuli in contrasting categories: Truncations due to boundaries. Journal of Experimental Psychology: General, 136, 502-519.

Huttenlocher, J., Vasilyeva, M., Vevea, J., Waterfall, H. R., & Hedges, L. V. (2007). Varieties of speech in young children. Developmental Psychology, 43, 1062-1083.

Crawford, E., J. Huttenlocher, and L. V. Hedges. 2006. Within-category feature correlations and Bayesian adjustment strategies. Psychonomic Bulletin and Review, 13, 245-250.

Klibanoff, R., S. C. Levine, J. Huttenlocher, M. Vasilyeva, and L. V. Hedges. 2006. Preschool children’s mathematical knowledge: The effect of teacher input. Developmental Psychology, 42, 59-69.

Huttenlocher, J., L. V. Hedges, B. Corrigan, and E. Crawford. 2004. Spatial categories and the estimation of location. Cognition 93:75-97.

Huttenlocher, J., Hedges, L. V., and Vevea, J. L. 2000. Why do categories affect stimulus judgment? Journal of Experimental Psychology (general) 129:1-22.

Sociology
Konstantopoulos, S., M. Modi, and L. V. Hedges. 2001. Who are America’s gifted? American Journal of Education 109:344–82.

Hedges, L. V., and A. Nowell. 1999. Changes in the black-white gap in achievement test scores: The evidence from nationally representative samples. Sociology of Education 72:111–35.

Nowell, A., and L. V. Hedges. 1998. Trends in gender differences in academic achievement from 1960 to 1994: An analysis of differences in mean, variance and extreme scores. Sex Roles 39:21–43.

Hedges, L. V. and A. Nowell, A. 1998. Are black-white differences in test scores narrowing? in The Black White Test Score Gap, ed. C. Jencks and M. Phillips, 254-81. Washington, DC: The Brookings Institution.

Research in Biology, Medicine or Public Health Publications

Mullen, P. D., G. Ramírez, D. Strouse, L. V. Hedges, and E. Sogolow. 2002. Meta-analysis of the effects of behavioral HIV prevention interventions on the sexual risk behavior of sexually experienced adolescents in U.S.-controlled studies. Journal of Acquired Immune Deficiency Syndromes 30:S94–105.

Hedges, L. V., W. Johnson, S. Semaan, and E. Sogolow. 2002. Theoretical issues in the synthesis of HIV prevention research. Journal of Acquired Immune Deficiency Syndromes 30:S8–14.

Neuman, M. S., W. D. Johnson, S. Semaan, S. A. Flores, G. Peersman, L. V. Hedges, and E. D. Sogolow. 2002. Review and meta-analysis of HIV prevention intervention research for heterosexual adult population in the United States. Journal of Acquired Immune Deficiency Syndromes 30:S106-117.

Semaan, S., D. DesJarlais, E. Sogolow, W. Johnson, L. V. Hedges, G. Ramírez, S. Flores, L.V. Norman, M. Sweat, and R. Needle. 2002. A meta-analysis of the effect of HIV prevention programs on the sex behaviors of drug users in the United States. Journal of Acquired Immune Deficiency Syndromes 30:S73-93.

Johnson, W., L. V. Hedges, G. Ramírez, S. Seeman, L. Norman, E. Sogolow, M. Sweat, and M. Diaz, 2002. HIV prevention research for men who have sex with men: A systematic review and meta-analysis. Journal of Acquired Immune Deficiency Syndromes 30:S118–130.

Hedges, L. V., J. Gurevitch, and P. Curtis. 1999. The meta-analysis of response ratios in experimental ecology. Ecology 80:1150–56.