Bland Altman Plots. Andrea Padoan, Dicember 2008

Bland Altman plot is a method of data plotting to assess agreement between two different assays

Description

INPUT:
3 columns array.
column1 (the left): sample ID or sample number
column2 and column3: instrument1 and instrument 2 outout

GRAPH OUTPUT:
Bland Altman scatter plot with mean difference line and +-2 SD lines.

CONSOLE OUTPUT:
diffmean = mean of the difference (the same you see in plot)
sdev = standard deviation of the differences.
 

• MATLAB release: MATLAB 7.4 (R2007a)

[Dan]

Works fine except the labels for the positive & negative 1.96*SD is not placed exactly right. You need to correct the text function calls and offset the y coordinate by diffmean like this:

text (maxx, twosdev+diffmean, ' 1.96 sd ', 'Color', 'b' , 'FontSize', 12, 'FontWeight', 'bold');

text (maxx, -twosdev+diffmean, ' -1.96 sd', 'Color', 'b' , 'FontSize', 12, 'FontWeight', 'bold');

Dan