On Wednesday 21 April 2004 11:19, you wrote:
> Hi - what you are doing sounds right. Is it possible that by some chance
> the 3 predictor EVs _do_ actually add up to a constant? Have a look at the
> "Covariance" - is the bottom-right square black?
>
> Cheers, Steve.
>
> On Wed, 21 Apr 2004, Appu Mohanty wrote:
> > Hi,
> >
> > I am trying to do a regression analyses using the functional data as DV
> > and three questionnaire measures as predictors. Since, the EV's are not
> > demeaned at the higher level of analyses, I mean centered (EV value -
> > mean of EV) the EV's beforehand. I then included an EV consisting of 1's
> > (modeling group mean) and three mean centered EV's corresponding to the
> > three predictors in the model. I get an error message stating "at least
> > one EV is a linear combination of other..." I do not get this error if I
> > include only the three EV's corresponding to the predictors and not the
> > EV modeling the group mean. It appears that adding the EV modeling the
> > group mean adds some linear dependency in the model. I am not sure why
> > this is happening or how to proceed next. I would appreciate any
> > suggestions.
> >
> > thanks
> > Appu
>
> Stephen M. Smith DPhil
> Associate Director, FMRIB and Analysis Research Coordinator
>
> Oxford University Centre for Functional MRI of the Brain
> John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
> +44 (0) 1865 222726 (fax 222717)
>
> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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