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, matplotlib, and ggplot2 libraries, Stata through the vioplot add-in, and the Python library Matplotlib.
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.
- "What's new in matplotlib: violin plots"
- gr45 - A turnip graph engine, Steve Woloshin, VA Outcomes Group, VA Medical Center, White River Junction, VT 
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