modeest (version 1.06)

dip: Compute Hartigan's DIP Test Statistic for Unimodality

Description

Computes Hartigan's DIP test statistic for testing unimodality, and additionally the modal interval. This function is taken from Martin Maechler's diptest package.

Usage

dip(x, 
    full.result = FALSE, 
    debug = FALSE)

Arguments

x

numeric. Vector of observations.

full.result

logical. If TRUE returns the full result list, see below.

debug

logical. If TRUE, some tracing information is printed (from the C routine).

Value

• Depending on full.result either a number, the dip statistic, or a list with components
• x
  the sorted unname()d data.
• n
  length(x).
• dip
  the dip statistic
• lo.hi
  indices into x for lower and higher end of modal interval
• xl, xu
  lower and upper end of modal interval
• gcm, lcm
  (last used) indices for greatest convex minorant and the least concave majorant.
• mn, mj
  index vectors of length n for the GC minorant and the LC majorant respectively.

References

• Hartigan J.A. and Hartigan P.M. (1985). The Dip Test of Unimodality.Ann. Statist.,13:70-84.
• Hartigan P.M. (1985). Computation of the Dip Statistic to Test for Unimodality.Appl. Statist. (JRSS C),34:320-325.

See Also

isoreg for isotonic regression.

Examples

data(precip)
plot(density(precip))
str(dip(precip, full = TRUE, debug = TRUE))