Plotting method to investigate the result of function ampute. 
Based on lattice. bwplot produces box-and-whisker plots of 
the relation between the data variables and the amputed data. The function does 
not show which data is amputed. It does show how the amputed values are related 
to the variable values.
# S3 method for mads
bwplot(x, yvar = NULL, which.pat = NULL,
  standardized = TRUE, descriptives = TRUE, layout = NULL)A mads (mads-class) object, typically created by 
ampute.
A string or vector of variable names that needs to be plotted. As a default, all variables will be plotted.
A scalar or vector indicating which patterns need to be plotted. As a default, all patterns are plotted.
Logical. Whether the box-and-whisker plots need to be created from standardized data or not. Default is TRUE.
Logical. Whether the mean, variance and n of the variables need to be printed. This is useful to examine the effect of the amputation. Default is TRUE.
A vector of two values indicating how the boxplots of one pattern
should be divided over the plot. For example, c(2, 3) indicates that the 
boxplots of six variables need to be placed on 3 rows and 2 columns. Default
is 1 row and an amount of columns equal to #variables. Note that for more than 
6 variables, multiple plots will be created automatically.
A list containing the box-and-whisker plots. Note that a new pattern will always be shown in a new plot.
ampute, bwplot, Lattice for 
an overview of the package, mads-class