We don't deal with it in the GLM. The idea is that you should reject
corrupted trials first. If you just want to average then there is an
option to use robust averaging which is accessible via the 'Average'
button. If you want to do a regression over trials you could do a
robust GLM. We have code for that in spm_robust_glm. There is a
reference in the function for the paper on which it is based. But we
are not using this code at the moment.
Vladimir
On Fri, Nov 12, 2010 at 1:08 PM, Dr Cyril Pernet <[log in to unmask]> wrote:
> Hi Vlad,
>
> Yes I'm interested in the covariance matrix between trials - in short say
> you run a WLS but some trials are corrupted (outliers for various reasons),
> how SPM delas with this?
>
> The serial correlation could be dealt with an adaptative autoregressive
> filter I suppose but it doesn't help with outlier trials (which are
> correlated in space and time)
>
> Any help much appreciated
> Cyril
>
>
>> Dear Cyril,
>>
>> SPM treats trials as independent observations so it does not look at
>> covariance between them (like serial correlations or something of that
>> sort), if that's what you meant.
>>
>> Best,
>>
>> Vladimir
>>
>> On Fri, Nov 12, 2010 at 9:30 AM, Dr Cyril Pernet
>> <[log in to unmask]> wrote:
>>> Dear SPM developpers,
>>>
>>> I was wondering how is the covariance among trials of a given condition
>>> estimated. Does SPM use special estimates for MEEG (as opposed to fMRI)?
>>> if
>>> so would you mind pointing me in the right direction .. articles / part
>>> of
>>> the code ..
>>>
>>> Cheers
>>> Cyril
>>>
>>>
>>>
>>> --
>>> The University of Edinburgh is a charitable body, registered in
>>> Scotland, with registration number SC005336.
>>>
>>
>>
>
>
>
> --
> Dr Cyril Pernet,
> SBIRC fMRI manager
> Lecturer in cognitive neuroimaging
> SFC Brain Imaging Research Center
> Division of Clinical Neurosciences
> University of Edinburgh
> Western General Hospital
> Crewe Road
> Edinburgh
> EH4 2XU
> Scotland, UK
>
> [log in to unmask]
> tel: +44(0)1315373661
> http://www.sinapse.ac.uk/
> http://www.sbirc.ed.ac.uk/cyril
>
> --
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
>
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