The VBS Plot

The VBS plot is a superimposition of three plots: a violin plot, a box plot, and a 1D scatterplot. Its purpose is to visualize the distribution of a continuous variable. Unlike its primary competitor, the more traditional histogram, the VBS plot does not require binning of the values of the variable.

Box Plot

The box in a box plot of a continuous variable is based on the interquartile range or IQR, the positive difference between what is essentially the first and third quartiles, the range of data that contains the middle 50% of all the data values. The box’s width is the IQR, with a line through the median and perpendicular lines called whiskers extending out from the edges. The whiskers extend to the to respective small value and largest value that are not outliers, values considerable different from most remaining values of a distribution.

Violin Plot

The violin plot is an updated version of the boxplot that replaces the box with a density plot, a smoothed histogram, and its mirror image. The violin plot transforms the straight edges of the box into information that shows the concentration of data values along the horizontal axis. The general appearance of a density plot and its mirror image may sometimes resemble a violin, hence the name.

1D Scatterplot

The one-variable scatterplot plots a point for every data value along the same axis.

Parameters

For the full list of Plot() parameters, see the manual obtained by entering ?Plot. These listed parameters are those provided in the interactive session from interact("Trellis").

x-variable

The numerical variable from which to construct the VBS plot.

by1-variable

Optional categorical variable to create a Trellis for each level of the variable.

Points

fill
interior color of a bar
color
exterior color of a bar, i.e., its border
transparency
transparency level of 0 (none) to 1 (completely transparent)
size
size of the plotted points
shape
shape of the plotted points

Objects

vbs_plot
A character string that specifies the components of the integrated Violin-Box-Scatterplot (VBS) of a continuous variable. A "v" in the string indicates a violin plot, a "b" indicates a box plot with flagged outliers, and a "s" indicates a 1-variable scatterplot. Default value is "vbs". The characters can be in any order and upper- or lower-case.
violin_fill
interior color of each violin in a violin plot
box_fill
interior color of each box in a box plot

Jitter

jitter_y
jitter applied to the y-variable coordinates

Save

width
width of saved pdf file, in inches
height
height of saved pdf file, in inches