[R-sig-ME] Modeling polar coordinates

[Titus von der Malsburg]

On Wed, Aug 18, 2010 at 12:37:23PM -0300, Luciano Selzer wrote:
> I don't know if there's anything to deal with that builtin in lme4. But
> perhaps you could transform your polar coordinates to cartesian
> coordinates??

Hi Luciano.  Thanks for the suggestion but using cartesian coordinates
is unfortunately not possible.  I have one map for each experimental
item.  Each subject contributes one point to each map.  The maps where
derived using multi-dimensional scaling (MDS) and the solutions of MDS
are invariant to rotation.  This means that x- and y-axis do not mean
the same on those maps.  One goal of modeling the polar coordinates is
to find out how I have to rotate the maps in order to align them.  The
amount I have to rotate the maps would be given by the random
intercept for items.

  Titus