title: Funnel plots for comparing institutional performance.
abstract: 'Funnel plots' are recommended as a graphical aid for institutional comparisons, in which an estimate of an underlying quantity is plotted against an interpretable measure of its precision. 'Control limits' form a funnel around the target outcome, in a close analogy to standard Shewhart control charts. Examples are given for comparing proportions and changes in rates, assessing association between outcome and volume of cases, and dealing with over-dispersion due to unmeasured risk factors. We conclude that funnel plots are flexible, attractively simple, and avoid spurious ranking of institutions into 'league tables'.
authors.affiliation: MRC Biostatistics Unit, Institute of Public Health, Cambridge CB2 2SR, UK. david.spiegelhalter@mrc-bsu.cam.ac.uk
authors.forename: David J
authors.initials: DJ
authors.lastname: Spiegelhalter
mesh_terms: D000293:Adolescent; D001699:Biometry; D006348:Cardiac Surgical Procedures / Q000401:mortality; D001026:Coronary Artery Bypass / Q000401:mortality / Q000706:statistics & numerical data; D003430:Cross-Sectional Studies; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D016017:Odds Ratio; D017063:Outcome Assessment, Health Care; D011247:Pregnancy; D011253:Pregnancy in Adolescence / Q000517:prevention & control / Q000706:statistics & numerical data; D011785:Quality Assurance, Health Care; D012307:Risk Factors