Steve, thank you. Only one question, when you say you'd use
sqrt(VARCOPE) as "error-bars on the COPE" you mean the %SC transformed COPE?
cheers
martin
Steve Smith wrote:
> Hi - yes, this is straightforward:
>
> %SC = 100 * COPE * H / mean_func
>
> where H is the peak-peak-height equivalent for the relevant contrast,
> found in the header of design.con (see the estimability paper for more
> details on this).
>
> I would think you would want to just use sqrt(varcope) as errorbars on
> the cope.
>
> Cheers.
>
>
>
> On 21 Nov 2007, at 21:39, Martin M Monti wrote:
>
>> Dear FSLers,
>>
>> I know this has been asked in the past but i couldn't seem to find a
>> clear answer on the FSL website (please point me towards it if I
>> missed it..).
>> How do I convert higher-level cope (or pe) into % signal change?
>>
>> I know it has to do with the design, in my case I used a slow event
>> related in which the regressor height was always 1, and events are
>> sufficiently spaced in time that the amplitude of one should not be
>> affected by the preceding trial (about 14 sec fixation in between
>> each..)
>>
>> Also, is it correct to use, as errorbars for the cope the
>> varcope/sqrt(dof)?
>> On the other hand, how do I get errorbars when computing the average
>> % signal change (as I was asking above)?
>>
>> cheers
>>
>> martin
>
>
> ---------------------------------------------------------------------------
>
> 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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