What Do Limits Of Agreement Show

Carkeet A. Exact parametric confidence intervals for Bland-Altman match limits. Optom Vis Sci. 2015;92:e71–80. For the blood pressure data presented in Bland and Altman [2] with the sample size N = 85, the mean sample difference (observer minus machine) ( overline{X} ) = − 16.29 mmHg and the standard deviation of the differences S = 19.61 are the 95% confidence intervals of the exact method and two approximate methods for the 2.5th percentile {( widehat{uptheta} ) L , ( widehat{uptheta} ) U } = {− 62,9501, − 48.3770}, {( widehat{uptheta} ) AL , ( widehat{uptheta} ) AU } = {− 62.1035, − 47.5754} or {( widehat{uptheta} ) BAL and ( widehat{uptheta} ) BAU } = {− 61.9536, − 47.4961}. The large number of citations showed that Bland-Altman analysis has become the most important technique for evaluating the agreement between two clinical measurement methods. But the recent work of Carkeet [19] and Carkeet and Goh [20] has provided detailed discussions in favor of a precise confidence interval on the approximate procedure considered in Bland and Altman [1, 2], especially when sample sizes are small. Other considerations and reviews on the measurement of agreement in method comparison studies are available in Barnhart, Haber and Lin [21], Choudhary and Nagaraja [22] and Lin et al. [23]. Barnhart HX, Haber MJ, Lin LI. An overview of conformity assessment for continuous measures.

J Biopharm Stat. 2007;17:529–69. To compare the measurement systems with the Bland Altman method, the differences between the individual measurements of the two different measurement systems are calculated, and then the mean value and standard deviation are derived. . . .