initDispersionParameter function

Initialization of the dispersion parameter.

Initialize the dispersion parameter.

initDispersionParameter(
  tree,
  trait,
  center,
  method.init.disp = c("Qn", "Sn", "MAD", "IQR"),
  method
)

Arguments

• trait: named vector of traits at the tips.
• center: the center parameter of the distribution
• method.init.disp: the robust estimator method
• method: the method used to fit the process. One of reml (the default), fixed.root or random.root. See Details.

Returns

The initial dispersion parameter.

Details

Constants are taken from Rousseeuw & Croux, 1993.

References

Rousseeuw P.J., Croux C. 1993. Alternatives to the Median Absolute Deviation. Journal of the American Statistical Association. 88:1273–1283.