Optometry and vision science : official publication of the American Academy of Optometry
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The previous literature on Bland-Altman analysis only describes approximate methods for calculating confidence intervals for 95% limits of agreement (LoAs). This article describes exact methods for calculating such confidence intervals based on the assumption that differences in measurement pairs are normally distributed. ⋯ Exact confidence intervals for LoAs can differ considerably from the Bland and Altman approximate method, especially for sample sizes that are not large. There are better, more precise methods for calculating confidence intervals for LoAs than the Bland and Altman approximate method, although even an approximate calculation of confidence intervals for LoAs is likely to be better than none at all. Reporting confidence limits for LoAs considered as a pair is appropriate for most situations; however, there may be circumstances where it is appropriate to report confidence limits for LoAs considered individually.