Comparing methods of measurement: why plotting difference against standard method is misleading

✍ Scribed by J.M. Bland; D.G. Altman

• Book ID: 118558775
• Publisher: The Lancet
• Year: 1995
• Tongue: English
• Weight: 380 KB
• Volume: 346
• Category: Article
• ISSN: 0140-6736
• DOI: 10.1016/s0140-6736(95)91748-9

✦ Synopsis

When comparing a new method of measurement with a standard method, one of the things we want to know is whether the difference between the measurements by the two methods is related to the magnitude of the measurement. A plot of the difference against the standard measurement is sometimes suggested, but this will always appear to show a relation between difference and magnitude when there is none. A plot of the difference against the average of the standard and new measurements is unlikely to mislead in this way. We show this theoretically and by a practical example.