Validating the bland altman method of agreement
Some texts even use pairs of measurements by two different methods to illustrate the calculation of r.
Once the correlation approach has been published, others will read of a statistical problem similar to their own being solved in this way and will use the same technique with their own data. Estimation of gestational age at birth: comparison of two methods.
Medical statisticians who ask "why did you use this statistical method?
" will often be told "because this published paper used it". Measurement in medicine: the analysis of method comparison studies.
The second step is usually to calculate the correlation coefficient (r) between the two methods.
For the data in fig 1, r = 0.94 (p ), but if there are differences between the two methods not explicable by repeatability errors alone (i.e. Comparability of M-mode echocardiographic long axis and short axis left ventricular function derivatives.
We propose a new method of sample size estimation for Bland-Altman agreement assessment.Journals could help to rectify this error by returning for reanalysis papers which use incorrect statistical techniques. Referees, inspecting papers in which two methods of measurement have been compared, sometimes complain if no correlation coefficients are provided, even when the reasons for not doing so are given.