Editing Multimodal distribution (section)

==== Wang's index ====

The bimodality index proposed by Wang ''et al'' assumes that the distribution is a sum of two normal distributions with equal variances but differing means.<ref name=Wang2009>{{cite journal | last1 = Wang | first1 = J | last2 = Wen | first2 = S | last3 = Symmans | first3 = WF | last4 = Pusztai | first4 = L | last5 = Coombes | first5 = KR | year = 2009 | title = The bimodality index: a criterion for discovering and ranking bimodal signatures from cancer gene expression profiling data | journal = Cancer Informatics | volume = 7 | pages = 199–216 |doi=10.4137/CIN.S2846| pmid = 19718451 | pmc = 2730180 }}</ref> It is defined as follows:

<math display="block"> \delta = \frac{ | \mu_1 - \mu_2 |}{ \sigma } </math>

where ''μ''<sub>1</sub>, ''μ''<sub>2</sub> are the means and ''σ'' is the common standard deviation.

<math display="block"> BI = \delta \sqrt{ p( 1 - p ) } </math>

where ''p'' is the mixing parameter.