Hi Jason,
what I am usually doing wrong in this context is to either forget to
transpose the contrast (i.e., enter [1 -1 0] instead of [1 -1 0]' or
so), or to not include the constant term (1 zero) or the motion
parameters in the contrast (usually 6 zeros). It is odd, though, that
this only happens with some subjects. Have you automatically included a
file specifying a multiple regressor (such as the rp... file) which may
have the wrong format in this subject?
Cheers,
Marko
Jason Ozubko wrote:
> Hi all,
>
> I'm trying to track down the cause of an "Invalid Contrast" error
> message in my 1st-level analyses and I've hit a wall. I have a script
> that generates contrast vectors for subjects based on certain
> parameters, and the script worked for 5 subjects and on the 6th it
> didn't. Half way through the 6th subject I get an Invalid Contrast
> error message.
>
> I've checked the contrast vector that failed, and it sums to zero and it
> does not include any conditions with beta that cannot be estimated
> (i.e., all the conditions set to be contrasted are estimable according
> to the design matrix). Beyond these two things, I'm not sure what else
> would cause an "Invalid Contrast" error message and I haven't been able
> to find any information online. Has anyone got any ideas?
>
> Thanks!
>
> Cheers,
> Jason
>
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
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http://www.medizin.uni-tuebingen.de/kinder/epn/
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