Elsevier

The Lancet

Volume 346, Issue 8982, 21 October 1995, Pages 1085-1087
The Lancet

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

https://doi.org/10.1016/S0140-6736(95)91748-9Get rights and content

Abstract

Summary

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.

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