Plotting the Bland-Altman limits of agreement
Plot a difference plot and limits of agreement.
- Select a cell in the dataset.
-
On the Analyse-it ribbon tab, in the
Statistical Analyses group, click
Method Comparison(or Agreement
depending on the edition), and then click
Bland-Altman.
The analysis task pane opens.
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If the data are in 2 variables:
- In the X drop-down list, select the comparative or reference measurement procedure variable.
- In the Y drop-down list, select the test measurement procedure variable.
Note: If the variables consist of replicate measurements, select the variable name that spans all the replicate columns. -
If the data are in 2 variables with a separate variable identifying replicates of each item:
- In the X drop-down list, select the comparative or reference measurement procedure variable.
- In the Y drop-down list, select the test measurement procedure variable.
- In the Item drop-down list, select the variable identifying each item.
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If the data are in a single variable with a separate variable matching each item and a variable identifying the method:
- In the Model drop-down menu, select Matched Pairs.
- In the Y drop-down list, select the measurement variable.
- In the Item drop-down list, select the item variable that identifies each item.
- In the Method drop-down list, select the method variable.
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In the D drop-down list, select:
Option Description Difference Plot the differences on the vertical axis. Relative Difference Plot the differences relative to Z on the vertical axis. Ratio Plot the ratio of the values on the vertical axis. -
In the on Z drop-down list, select:
Option Description X Plot X as a reference method on the horizontal axis. (X+Y)/2 Plot the average on the horizontal axis. Neither X or Y are reference methods. -
In the Mean function drop-down list, select:
Option Description Constant There is a constant relationship between D and Z. Linear function There is a linear relationship between D and Z. -
In the SD drop-down list, select:
Option Description Constant The measurement error is constant throughout the measuring interval. Linear function The measurement error is linear across the measuring interval. - Click Calculate.
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