Bland & Altman Difference Plot

The Bland & Altman Method Comparison

  • The Bland & Altman method comparison compares two methods of measurement or two paired variables, and provides a plot of difference vs. mean, in which the standard deviation of differences between measurements made by the two methods provides an index of the comparability of the methods.
  • The confidence interval display options include:
    • ±1.96 standard deviation
    • Paired t-test CI (95%)
    • Paired t-test CI (99%)
Example Graph

Bland & Altman Plot Displaying the Difference vs. Mean for PEER Data*

Bland & Altman Difference Plot

* Source of data: Bland, J.M. and Altman, D.G. (1986). Statistical methods for assessing agreement between two methods of clinical measurement. Lancet, (i), 307-310.