Hi Steve,
I'm having a similar problem as Eric with empty EV's and contrasts. Is there
any update as to when the patch might be available?
Thanks,
Tyler
On Wed, 10 Oct 2007 16:24:06 +0100, Steve Smith <[log in to unmask]> wrote:
>Hi - yes, this should work - it's just a case of persuading FEAT that
>all is well. We've just made some minor amendments to the scripts to
>allow empty EVs to run through ok and even contrasts involving empty
>EVs (effectively assumes that the relevant PE is zero even though
>this can't be estimated properly). This will be released in the next
>patch release, probably next week.
>
>Cheers, Steve.
>
>
>On 28 Sep 2007, at 19:30, Eric Claus wrote:
>
>> FSLers,
>> I am trying to run first level analyses for each run of a 3-run
>> fMRI study.
>> Within each run, there are several trial types, but because the
>> classification of a trial depends on the participant's response,
>> there are
>> some cases where 1 or more trial types do not exist in a given
>> run. For
>> each trial type, I have a separate EV file and for the cases in
>> which no
>> trials exist, the empty EV option in FSL is chosen.
>>
>> 2 questions:
>>
>> 1. When trying to run the subject's model, I get a rank deficiency
>> message
>> which seems to be expected given the empty EVs. If all the other
>> EVs in the
>> model look correct (i.e. are not linear combinations of one
>> another), are
>> the results of the analysis valid?
>>
>> 2. If I have 4 EVs: EV1 EV2 EV3 EV4 and a given subject has an
>> empty EV for
>> EV2, how does this affect any contrast with EV2? For example, if a
>> contrast
>> of 1 -1 0 0 is used, is the resulting statistical map equivalent to
>> the
>> mean/fit for EV1 or should the stat map be zero, given that the two
>> conditions are not really being compared? Further, if the
>> participant has
>> valid trials for runs 2 and 3 in both EV1 and EV2, when I do the fixed
>> effects analysis for this subject, is the run1 contrast included in
>> the mean?
>>
>> Thanks in advance,
>> Eric
>
>
>------------------------------------------------------------------------
>---
>Stephen M. Smith, Professor of Biomedical Engineering
>Associate Director, Oxford University FMRIB Centre
>
>FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
>+44 (0) 1865 222726 (fax 222717)
>[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
>------------------------------------------------------------------------
>---
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