Description Usage Arguments Details Value Author(s) References See Also Examples
Sarle's bimodality coefficient.
1 | bimodality_sarle(x, bs.iter = 1, type = "Sarle.finite.sample")
|
x |
Data vector for which bimodality will be quantified |
bs.iter |
Bootstrap iterations |
type |
Score type ('Sarle.finite.sample' or 'Sarle.asymptotic') |
The coefficient lies in (0, 1).
The 'Sarle.asymptotic' version is defined as
b=(g^2 + 1) / k
. This is coefficient of bimodality from Ellison AM Am. J. Bot. 1987, for microbiome analysis it has been used for instance in Shade et al. 2014.
The formula for 'Sarle.finite.sample' (SAS 2012):
b=\frac{g^2 + 1}{k + (3(n-1)^2)/((n-2)(n-3))}
where n is sample size and
In both formulas, g is sample skewness and k is the kth standardized moment (also called the sample kurtosis, or excess kurtosis).
Bimodality score
Contact: Leo Lahti microbiome-admin@googlegroups.com
Shade et al. mBio 5(4):e01371-14, 2014.
Ellison AM (1987) Am J Botany 74(8):1280-1288.
SAS Institute Inc. (2012). SAS/STAT 12.1 user's guide. Cary, NC.
To cite the microbiome R package, see citation('microbiome')
Check the dip.test from the DIP package for a classical test of multimodality.
1 | # b <- bimodality_sarle(rnorm(50), type='Sarle.finite.sample')
|
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