Bihistogram
http://www.itl.nist.gov/div898/handbook/eda/section3/bihistog.htm
The bihistogram is an EDA tool for assessing whether a before-versus-after engineering modification has caused a change in
- location;
- variation; Or
- distribution.
It Is a graphical alternative To the two-sample t-test. The bihistogram can be more powerful than the t-test In that all Of the distributional features (location, scale, skewness, outliers) are evident on a single plot. It Is also based on the common And well-understood histogram.