He has authored a number of articles and books on statistical methods for meta-analysis, which is the use of statistical methods for combining results from different studies. He also suggested several estimators for effect sizes and derived their properties. He carried out research on the relation of resources available to schools and student achievement, most notably the relation between class size and achievement.
Hedges' g
In 1981, Hedges published a paper describing the unbiased standardized mean difference, the g statistic.[5] "It turns out that [Cohen's] d has a slight bias, tending to overestimate the absolute value of in small samples. This bias can be removed by a simple correction that yields an unbiased estimate of, with the unbiased estimate sometimes called Hedges’ g."[6]
Bibliography
Hedges, Larry V.; Olkin, Ingram (1985). Statistical methods for meta-analysis. Boston: Academic Press. ISBN0-12-336380-2.
Woodworth, George Walter; Hedges, Larry V.; Shymansky, James A. (1989). A practical guide to modern methods of meta-analysis. Arlington, VA: National Science Teachers Association. ISBN0-87355-081-1.
Hedges, Larry V.; Cooper, Harris M. (1994). The Handbook of research synthesis. New York: Russell Sage Foundation. ISBN0-87154-226-9.
Rothstein, Hannah; Borenstein, Michael; Hedges, Larry V. (2009). Introduction to Meta-Analysis (Statistics in Practice). New York: Wiley. ISBN978-0-470-05724-7.