title: Meta-analysis for orthodontists: Part I--How to choose effect measure and statistical model.
abstract: Systematic reviews ideally provide a comprehensive and unbiased summary of existing evidence from clinical studies, whilst meta-analysis combines the results of these studies to produce an overall estimate. Collectively, this makes them invaluable for clinical decision-making. Although the number of published systematic reviews and meta-analyses in orthodontics has increased, questions are often raised about their methodological soundness. In this primer, the first steps of meta-analysis are discussed, namely the choice of an effect measure to express the results of included studies, and the choice of a statistical model for the meta-analysis. Clinical orthodontic examples are given to explain the various options available, the thought process behind the choice between them and their interpretation.
authors.affiliation: Department of Orthodontics Department of Oral Technology, School of Dentistry, University of Bonn, Bonn, Germany.
authors.forename: Spyridon N
authors.initials: SN
authors.lastname: Papageorgiou
mesh_terms: D000465:Algorithms; D003627:Data Interpretation, Statistical; D055094:Evidence-Based Dentistry; D006801:Humans; D015201:Meta-Analysis as Topic; D015233:Models, Statistical; D061366:Numbers Needed To Treat / Q000706:statistics & numerical data; D016017:Odds Ratio; D009970:Orthodontics / Q000706:statistics & numerical data*; D012196:Review Literature as Topic
keywords: Effect measure; fixed-effect; meta-analysis; orthodontics; random-effects