Assessing Agreement between Methods of Measurement.

Abstract

Featured Article : Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;i:307–10.3 We began our careers as medical statisticians in the 1970s, working in an epidemiology department. The quality of measurements was well-recognized in epidemiology, as illustrated by the development of the “random-zero” sphygmomanometer to enable unbiased measurement of blood pressure. But it was after we had moved on to separate clinical research environments that we independently faced many scenarios relating to how to measure biological quantities, initially in the fields of rheumatology and cardiology. We discovered that the standard way in which measurement studies were then analyzed was by correlation coefficients, whether authors were comparing measurements obtained by different observers using the same method or measurements obtained using different methods. It was obvious to us that correlation did not provide a useful answer to the agreement between 2 methods of measurement. For example, we could double the size of all the observations …