Degree of bimodality is an important feature of a frequency distribution, because it could suggest heterogeneity, such as polarization or two underlying distributions combined into one. The literature contains several measures of bimodality. This article attempts to summarize most of those measures, with their attendant advantages and disadvantages.
Knapp, Thomas R.
Journal of Modern Applied Statistical Methods:
1, Article 3.
Available at: http://digitalcommons.wayne.edu/jmasm/vol6/iss1/3