Violin plots are a method of plotting numeric data. A violin plot is a combination of a box plot and a kernel density plot. Specifically, it starts with a box plot. It then adds a rotated kernel density plot to each side of the box plot.
The violin plot is similar to box plots, except that they also show the probability density of the data at different values (in the simplest case this could be a histogram). Typically violin plots will include a marker for the median of the data and a box indicating the interquartile range, as in standard box plots. Overlaid on this box plot is a kernel density estimation.
Violin plots are available as extensions to a number of software packages, including R through the vioplot, wvioplot, caroline, UsingR, lattice, and ggplot2 libraries, and Stata through the vioplot add-in.
Violin plots are also quite similar to the turnip graph used in STATA.
- VIOLIN PLOT. www.itl.nist.gov. Retrieved 14 October 2008.
- Hintze, Jerry L., and Ray D. Nelson. 1998. "Violin Plots: A Box Plot-Density Trace Synergism." The American Statistician 52(2):181-84.
- gr45 - A turnip graph engine, Steve Woloshin, VA Outcomes Group, VA Medical Center, White River Junction, VT 
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