Limits of Agreement Summary
Calculate descriptive Bland–Altman limits from the mean and SD of paired measurement differences.
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Summarize approximate 95% limits of agreement from the mean and SD of paired differences. Enter the SD of differences, not either instrument’s marginal SD. All default values are fictional.
Calculation results
-3.88 to 7.88
Approximate 95% limits of agreement. Mean difference: 2; 50 independent pairs.
Assumptions and limits
Descriptive limits = mean difference ± 1.96 × SD of differences. These are not a confidence interval for the mean or for the limits, and are not exact small-sample prediction limits. Roughly normal differences with stable spread and independent pairs are required for the usual interpretation. Summary inputs cannot reveal proportional bias, outliers or heteroscedasticity; inspect the difference-versus-mean plot. Repeated pairs per person need extended methods. Sample size is recorded but does not alter these plug-in limits. Acceptability must be defined in outcome units in advance; these numbers do not establish interchangeability.
Bland and Altman: agreement between measurement methods · Read the practical guide · Download blank worksheet (TXT)