On 13 Dec 2010, at 20:12, Nick Cox wrote:
> I can't see much point to plots of the form re-invented by Bland and Altman in this case. Nor does the limits of agreement approach transfer other than queasily to a 4-point graded scale. -tabplot- from SSC offers one of various graphical alternatives. Diagonal agreement and off-diagonal disagreement will be pretty clear.
A scatterplot with a large jitter can also be interesting, especially were there are more than two raters.
As a matter of historical trivia, Bland and Altman didn't claim to have invented the plot, nor did they give it a name in their original paper. The paper, however, became a citation classic (I believe it is the most cited paper the Lancet ever published) and more or less single-handedly eradicated inappropriate analysis of agreement data in biomedicine, something for which we should all be grateful as we get older.
Ronán Conroy
rconroy@rcsi.ie
Associate Professor
Division of Population Health Sciences
Royal College of Surgeons in Ireland
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