[R] strucchange: breakpoints in inequally spaced data

Thomas Petzoldt thpe at hhbio.wasser.tu-dresden.de
Fri Jul 16 17:52:14 CEST 2004


we want to identify breakpoints (different phases) in environmental 
data, algae cell counts of three years with intervals between 7 and 30 
days (N=40). We found that

breakpoints(cells ~1)

works great and identifies 5 very good breaks, however we are uncertain 
about these, because the data are unequally spaced. Is there a way to 
include the information about the measurement intervals, e.g.

breakpoints(cells[-1] ~ diff(time))

Furthermore we wonder, why the OLS-CUSUM indicates several of these 
breakpoints but does not mark them as significant.

Thanks in advance!

Thomas P.

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