I was thinking of another condition, but you would also have to remove
these onsets from the onset vector that now includes all trials. I was
thinking of it along the lines of a nuisance regressor that captures the
trials you want to model (e.g. missing response trials), but not in your
regressors of interest. Does that make sense?
Jan
Dorian P. wrote:
> Hi Jan,
>
> Are you suggestingt another modulation or another condition?
>
> I have a collapsed condition including all trials and then using
> parametric modulation to distinguish between them. If I add another
> condition it will repeat some of the onset vectors of the first and
> the betas will not be uniqely specified. At that point I am not sure
> if parametric modulations would still be available for contrasting (or
> correctly evaluated).
>
> Dorian.
>
>
>
> 2009/2/5 Jan Gläscher <[log in to unmask]>:
>> Hi Dorian,
>>
>> why not model those trials in a different regressor?
>>
>> Cheers,
>> Jan
>>
>> Dorian P. wrote:
>>> Hi SPM list,
>>>
>>> I made this question some time ago but still didn't get a response.
>>>
>>> I want to leave out some of the trials in a parametric modulation
>>> regressor. Is there a way to do this?
>>>
>>> I would have thought to put "0" in the modulation of those trials but
>>> it doesn't seem clever if the other values are "1", "2", "3", "4". It
>>> may take the zero and use it in the modulation as simply less then
>>> one.
>>>
>>> Any clue please?
>>>
>>> Dorian.
>>> Ruhr University Bochum.
>>>
>> --
>> Jan Gläscher, Ph.D. Div. Humanities & Social Sciences
>> +1 (626) 395-3898 (office) Caltech, Broad Center, M/C 114-96
>> +1 (626) 395-2000 (fax) 1200 E. California Blvd
>> [log in to unmask] Pasadena, CA 91125
>>
>>
>
--
Jan Gläscher, Ph.D. Div. Humanities & Social Sciences
+1 (626) 395-3898 (office) Caltech, Broad Center, M/C 114-96
+1 (626) 395-2000 (fax) 1200 E. California Blvd
[log in to unmask] Pasadena, CA 91125
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