UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Statistical Primer: heterogeneity, random- or fixed-effects model analyses?

Barili, F; Parolari, A; Kappetein, PA; Freemantle, N; (2018) Statistical Primer: heterogeneity, random- or fixed-effects model analyses? Interactive CardioVascular and Thoracic Surgery , 27 (3) pp. 317-321. 10.1093/icvts/ivy163. Green open access

[thumbnail of Freemantle_Heterogeneity Final.pdf]
Preview
Text
Freemantle_Heterogeneity Final.pdf - Accepted Version

Download (885kB) | Preview

Abstract

Heterogeneity in meta-analysis describes differences in treatment effects between trials that exceed those we may expect through chance alone. Accounting for heterogeneity drives different statistical methods for summarizing data and, if heterogeneity is anticipated, a random-effects model will be preferred to the fixed-effects model. Random-effects models assume that there may be different underlying true effects estimated in each trial which are distributed about an overall mean. The confidence intervals (CIs) around the mean include both within-study and between-study components of variance (uncertainty). Summary effects provide an estimation of the average treatment effect, and the CI depicts the uncertainty around this estimate. There are 5 statistics that are computed to identify and quantify heterogeneity. They have different meaning and give complementary information: Q statistic and its P-value simply test whether effect sizes depart from homogeneity, T2 and T quantify the amount of heterogeneity, and I2 expresses the proportion of dispersion due to heterogeneity. The point estimate and CIs for random-effects models describe the practical implications of the observed heterogeneity and may usefully be contrasted with the fixed-effects estimates.

Type: Article
Title: Statistical Primer: heterogeneity, random- or fixed-effects model analyses?
Event: 31st Annual Meeting of the European-Association-for-Cardio-Thoracic-Surgery
Location: Vienna, AUSTRIA
Dates: 07 October 2017 - 11 October 2017
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/icvts/ivy163
Publisher version: http://doi.org/10.1093/icvts/ivy163
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Statistical analysis, Meta-analysis
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > Inst of Clinical Trials and Methodology > Comprehensive CTU at UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10056361
Downloads since deposit
474Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item