[R] calculating mean direction (CircStats)

[Cordula Becker]

Hi,

I've currently to work with some circular data. Unfortunately I'm not very
familiar with circular statistics and would really appreciate if I could get
some help concerning the CircStats package this way.

My data lies in the range 0 to 2*pi, and is transformed to radians (as
expected by the CircStats methods). Calculating the mean direction
(circ.mean) results for some datasets in a negative mean direction
like -0.8309982. I think that this might be wrong. If it is correct, what is
the meaning of a negative mean direction?

I also read that some transformation of the data might be necessary to get
the correct mean direction (multiplying all angles by two and taking the
modulus of these angles and 360°). I manage to do so, but I'm not sure about
how to back-transfer the mean direction I'm getting as a result to the
angles of my original data.

I would be very happy if anybody has some hints concerning this problem.

Thanks a lot, Cordula Becker
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Cordula Becker

Ludwig-Maximilians-Universität München
Allgemeine und Experimentelle Psychologie

Leopoldstr.13
D-80802 München
Germany

Tel. +49 (89) 2180 6231
Fax. +49 (89) 2180 5211