Lin's concordance correlation coefficient which is not model based, is very similar to model- based procedures discussed in the Shrout and Fleiss article. Lin does provide an excellent discussion of the failings of t-tests and the use of the ordinary correlation coefficient in such settings. However in most settings I would advocate the use of model-based approaches such as those proposed by Shrout and Fleiss, over the method that Lin has proposed.
Another useful reference in this context, is the article Altman, DG, and Bland, JM. (1983) "Measurement in medicine: the analysis of method comparison studies", The Statistician, 32: 307-317. I have never heard of the Bradley-Blackwood procedure. Do you have a reference for it? Shrout, P.E., and Fleiss, J.L "Intraclass correlations: uses in assessing rater reliability," Psychological Bulletin, 1979, 86, 420-428. SR Millis wrote: > Rich Ulrich wrote: > > For contrasting 2 raters, I like using a paired t-test and the > > corresponding interclass correlation. That shows you both > > the main pieces of information, without confusing them or > > confounding them at all. You get r to measure parallelism; > > you get t to measure mean-difference. > > Lin has discussed the shortcomings of the t-test for assessing > concordance between raters (Biometrics, 1989, 45, 255-268). Among other > things, the paired t-test fails to detect poor agreement in pairs of > data such as (1,3)(2,3)(3,3)(4,3)(5,3). > > Pearson correlation coefficient can be a good starting point for > detecting lack of agreement. But, a high r doesn't necessarily indicate > agreement. As a follow-up, Lin's concordance correlation coefficient or > the Bradley-Blackwood procedure can be useful supplements. > > SR Millis > . > . > ================================================================= > Instructions for joining and leaving this list, remarks about the > problem of INAPPROPRIATE MESSAGES, and archives are available at: > . http://jse.stat.ncsu.edu/ . > ================================================================= -- Roy St. Laurent Mathematics & Statistics Northern Arizona University http//odin.math.nau.edu/~rts . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
