Hello Eve,
that is very puzzling indeed, but one thing that comes to mind (as I
have been guilty of that in the past :) would be different version of
spm_defaults.m, which could be in a folder on top of spm proper, and
would thus not be overriden by using the same spm installation (and
settings pertaining to interpolation and spatial processing could
explain small differences). Does
which spm_defaults.m
point to the same file? Also (along the lines of what Donald suggested),
make sure you do not use data that has partly been processed (changed
header information or so). Other than that, no idea.
Good luck,
Marko
Huber Eveline wrote:
> Dear all,
>
> My colleague and me are working on the same data set. In order to double
> check our steps, we compared our data set after 1^st level processing.
> We used the exactly same data, the same batch for preprocessing, the
> same batch for 1^st level and we are having the same version of MATLAB
> and SPM8 (and also the same up-dates). We both work on Windows 7, but we
> don’t have the same computer.
>
> Anyway, we are not gaining the same results. It always looks more or
> less the same, but it seems like we’re having a slight shift of our data
> in almost all recorded subjects (e.g. my peak for a certain tasks says
> [18 -88 1] whereas hers is [18 -90 2]). Also, in her 1^st level
> analysis, the pattern of the clusters looks similar to mine but hers are
> increased in size (e.g my kE value says 66 and hers 131).
>
> We copied her SPM8 folder to my computer, set all the path exactly the
> same way and run one dataset of one subject again. Now we’re getting a
> third pattern, the activation differs in peak and cluster size again. If
> I adapt the Height threshold T to the value from my first analysis or to
> the one of my colleague, the exact values still differ from each other.
>
> How is this Height threshold set and from what does it depend on?
>
> Do you have any idea, we are not getting the same results even though we
> use exactly the same stuff?
>
> Thanks a lot for your help in advance,
>
> Best,
>
> Eve
>
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--
____________________________________________________
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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