The boundaries of the agreement (LoA) are defined as the average difference ± 1.96 SD of differences. If these limits do not exceed the maximum allowable difference between methods (differences in average value ± 1.96 SD are not clinically important), the two methods are considered consistent and can be used interchangeably. with – BAL – p N1.2 – t1 – α/2 (b1.2) and – BAU – z n1.2 – t1 – α/2 () b1/2. In the particular case of α – 0.05, general expressions are reduced to confidence intervals for the two points of evaluation of the 95% agree limits considered in Bland and Altman [2]: A Bland-Altman diagram (differential diagram) in chemistry or biomedicine is a method of presentation of data used for the analysis of the agreement between two different assays. It is identical to a tube of average difference Tukey,[1] the name under which it is known in other areas, but it was popularized in the medical statistics of J. Martin Bland and Douglas G. Altman. [2] [3] Barnhart HX, Haber MJ, Lin LI. An overview of the assessment of compliance with ongoing measures. J Biopharm Stat. 2007;17:529-69.

Carkeet A, Goh YT. Confidence and coverage for Bland-Altman limits the agreement and their approximate confidence intervals. Med Res Stat Methods. 2018;27:1559-74. A percentile is a numerical measure that represents the reference point below which a certain percentage of the target population values decreases. Because of the conceptual simplicity and the uns contextal characteristic, percentiles are often used to determine the relative size and essential importance of quantitative measurements in all scientific fields. For example, children`s health conditions are often assessed on the basis of weight and height relative to national averages and national percentiles in growth charts. In addition, reference limits in medicine and related fields are widely applied to identify an informative amount of measurement from a reference population. The most typical reference limits are the central 95% of the interest population.

As an important application, Bland and Altman`s compliance limits [1, 2] are composed of 95% of the 2.5th percentile and the 97.5th percentile for the distribution of the difference between the melted measurements. c) In order to determine the limits of compliance on the Bland-Altman plot, differences in systolic blood pressure measurements were accepted as carkeet A. Exact parametric confidence intervals for the Bland-Altman agreements. Optom Vis Sci. 2015;92:e71-80. The diagram shows a dispersal diagram of the differences represented by the average values of the two measures. The horizontal lines are drawn at the average difference and the limits of the match. Choudhary PK, Nagaraja HN. Measuring compliance in method comparison studies – an audit. In: Balakrishnan N, Kannan N, Nagaraja HN, editor. Investment and selection progress, multiple comparisons and reliability.

Boston: Birkhauser; 2004. 215-44. Bland JM, DG Altman. The measurement agreement in method comparison studies. Med Res Stat Methods. 1999;8:135-60. Bland and Altman indicate that two methods developed to measure the same parameter (or property) should have a good correlation if a group of samples is selected so that the property to be determined varies considerably.