Thanks Michael,
To recap - a problem with non-uniquely specified regressors, when all appear
unique.
I've checked... n-u-s regressors appear unique but have few values; e.g.:
8.181
5.195
8.914
These values are not replicated in any other regressor that I can see. I've
redone the model from scratch - please see attached. It's really strange
that in e.g. session 3,
(a) the regressor is not uniquely specified
(b) the regressor itself does vary (see above values)
(c) it is not identical to any other regressor in this session (suggesting
it is uniquely specified)
Any assistance much appreciated
***
Dear Christopher,
please check if your parameters really vary for the critical sessions or
have the same value for all trials of this condition.
Michael.
Am 19.02.2010 17:17, schrieb Christopher Benjamin:
> Dear SPM ninjas
>
> We have a problem with a first level model (see attached design matrix). We
> specify a model containing 4 sessions. Each has 2 conditions with a series
> of parametric modulations. After specification, the design matrix reveals 3
> greyed (“not uniquely specified”) regressors.
>
> The the grey regressors occur in the parametric modulations, and are the
> last regressor in the third session and the last 2 parameters of the fourth
> session.
>
> When the .mat file is checked, all the regressor values appear correct and
> appear to be uniquely specified.
>
> Any help would be much appreciated!
>
> Cheers
>
> Chris
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Dr. Michael Erb
Sektion f. experimentelle Kernspinresonanz des ZNS
Abteilung Neuroradiologie, Universitaetsklinikum
Hoppe-Seyler_Str. 3, D-72076 Tuebingen
Tel.: +49(0)7071/2987753 priv. +49(0)7071/61559
Fax.: +49(0)7071/294371
e-mail: <[log in to unmask]>
www: http://www.medizin.uni-tuebingen.de/nrad/sektion/
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