Author(s): Higgins JP, Thompson SG
The extent of heterogeneity in a meta-analysis partly determines the difficulty in drawing overall conclusions. This extent may be measured by estimating a between-study variance, but interpretation is then specific to a particular treatment effect metric. A test for the existence of heterogeneity exists, but depends on the number of studies in the meta-analysis. We develop measures of the impact of heterogeneity on a meta-analysis, from mathematical criteria, that are independent of the number of studies and the treatment effect metric. We derive and propose three suitable statistics: H is the square root of the chi2 heterogeneity statistic divided by its degrees of freedom; R is the ratio of the standard error of the underlying mean from a random effects meta-analysis to the standard error of a fixed effect meta-analytic estimate, and I2 is a transformation of (H) that describes the proportion of total variation in study estimates that is due to heterogeneity. We discuss interpretation, interval estimates and other properties of these measures and examine them in five example data sets showing different amounts of heterogeneity. We conclude that H and I2, which can usually be calculated for published meta-analyses, are particularly useful summaries of the impact of heterogeneity. One or both should be presented in published meta-analyses in preference to the test for heterogeneity.
Referred From: https://www.ncbi.nlm.nih.gov/pubmed/12111919
Author(s): Kurman RJ, Norris HJ
Author(s): Lacey JV Jr, Ioffe OB, Ronnett BM, Rush BB, Richesson DA, et al.
Author(s): Reed SD, Newton KM, Clinton WL, Epplein M, Garcia R, et al.
Author(s): Kurman RJ, Shih IeM
Author(s): Lacey JV Jr, Sherman ME, Rush BB, Ronnett BM, Ioffe OB, et al.
Author(s): Ferenczy A
Author(s): Stein CJ, Colditz GA
Author(s): Reed SD, Newton KM, Garcia RL, Allison KH, Voigt LF, et al.
Author(s): Ricci E, Moroni S, Parazzini F, Surace M, Benzi G, et al.
Author(s): Bobrowska K, Kamiński P, Cyganek A, Pietrzak B, Jabiry-Zieniewicz Z, et al.
Author(s): Heller DS, Mosquera C, Goldsmith LT, Cracchiolo B
Author(s): Gregoriou O, Konidaris S, Vrachnis N, Bakalianou K, Salakos N, et al.
Author(s): DerSimonian R, Kacker R
Author(s): Higgins JP, Thompson SG, Deeks JJ, Altman DG
Author(s): Egger M, Davey Smith G, Schneider M, Minder C
Author(s): Epplein M, Reed SD, Voigt LF, Newton KM, Holt VL, et al.
Author(s): Cheung AP
Author(s): Viola AS, Gouveia D, Andrade L, Aldrighi JM, Viola CF, et al.
Author(s): Kreiger N, Marrett LD, Clarke EA, Hilditch S, Woolever CA
Author(s): Weir HK, Sloan M, Kreiger N
Author(s): Epplein M, Reed SD, Voigt LF, Newton KM, Holt VL, et al.
Author(s): Nagamani M, Urban RJ
Author(s): Al-Jarrah M, Matalka I, Aseri HA, Mohtaseb A, Smirnova IV, et al.
Author(s): Guh DP, Zhang W, Bansback N, Amarsi Z, Birmingham CL, et al.
Author(s): Tankó LB, Christiansen C
Author(s): Midgette AS, Baron JA
Author(s): Cramer DW, Barbieri RL, Muto MG, Kelly A, Brucks JP, et al.
Author(s): Willett W, Stampfer MJ, Bain C, Lipnick R, Speizer FE, et al.
Author(s): Gandini S, Botteri E, Iodice S, Boniol M, Lowenfels AB, et al.
Author(s): Botteri E, Iodice S, Bagnardi V, Raimondi S, Lowenfels AB, et al.
Author(s): Thune I, Furberg AS
Author(s): Schonfeld SJ, Hartge P, Pfeiffer RM, Freedman DM, Greenlee RT, et al.
Author(s): Benshushan A, Paltiel O, Rojansky N, Brzezinski A, Laufer N
Author(s): Parslov M, Lidegaard O, Klintorp S, Pedersen B, Jønsson L, et al.
Author(s): Kelsey JL, LiVolsi VA, Holford TR, Fischer DB, Mostow ED, et al.
Author(s): Elwood JM, Cole P, Rothman KJ, Kaplan SD
Author(s): Parazzini F, La Vecchia C, Moroni S, Chatenoud L, Ricci E