# robustBAplot

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

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

- Keywords
- robustBAplot

##### Usage

```
robustBAplot(a, b, z = 1.96, methAlab = "Method A",
methBlab = "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).

- methAlab
Label to be used in the returned chart to refer to the method yielding the first set of measurements.

- methBlab
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

```
# NOT RUN {
#create a first toy vector
a <- rnorm(30,10,1)
#create a second toy vector
b <- a*runif(30,1,1.5)
robustBAplot(a,b)
# }
```

*Documentation reproduced from package GmAMisc, version 1.1.1, License: GPL (>= 2)*