robustBAplot: R function to plot a robust version of the Bland-Altman plot

In gianmarcoalberti/GmAMisc: Gianmarco Alberti Miscellaneous

Description

The function allows to plot a robust version of the Bland-Altman plot.

Usage

robustBAplot(a, b, z = 1.96, meth_A_lab = "Method A",
  meth_B_lab = "Method B", cex = 0.6)

Arguments

a:	vector storing the first set of measurements to be compared.
b:	vector storing the second set of measurements to be compared.
z:	value for the confidence interval for the median difference; set by default to 1.96 (corresponding to 95 percent CI).
meth_A_lab:	label to be used in the returned chart to refer to the method yielding the first set of measurements.
meth_B_lab:	label to be used in the returned chart to refer to the method yielding the second set of measurements.
cex:	size of the data points.

Details

The function returns a chart based on robust (i.e. resistant to outlying values) measures of central tendency and variability: median and Median Absolute Deviation (MAD) (Wilcox R R. 2001. "Fundamentals of modern statistical methods: Substantially improving power and accuracy". New York: Springer) instead of mean and standard deviation.
The x-axis displays the median of the two variables being compared, while the y-axis represents their difference. A solid horizontal line represents the bias, i.e. the median of the differences reported on the y-axis. Two dashed horizontal lines represent the region in which 95percent of the observations are expected to lie; they are set at the median plus or minus z*(MAD/0.6745).

Examples

a <- rnorm(30,10,1) #create a first toy vector
b <- a*runif(30,1,1.5) #create a second toy vector
robustBAplot(a,b) #returns the robust BA plot

gianmarcoalberti/GmAMisc documentation built on May 3, 2019, 6:44 p.m.