Hi - you can just take the residuals (take root of sigmasquareds) and
divide by sqrt(ntimepoints) to get standard deviation of the mean_func
- I'm pretty sure that's close enough....?
Cheers.
On 23 Jun 2009, at 10:50, Luis Hernandez wrote:
> right ... there is not Beta_hat_0 in FSL - it's just my way of
> saying estimate of baseline regressor parameter - (the one I'm
> after). In case you're wondering, I'm trying to use it to estimate
> spin density.
>
> thanks again
>
> -L
>
>
> On Jun 23, 2009, at 12:23 PM, Mark Jenkinson wrote:
>
>> Hi,
>>
>> In FSL there is no pe0 or beta_hat_0 file as we remove
>> the mean prior to setting up the GLM. Hence there is
>> no constant (mean) regressor and so no parameter estimate
>> (or variance) associated with that.
>>
>> I'm not sure where you are getting Beta_hat_0 from.
>>
>> All the best,
>> Mark
>>
>>
>> On 23 Jun 2009, at 16:28, Luis Hernandez wrote:
>>
>>> thanks, Mark.
>>>
>>> Beta_hat_0 is the same as the mean (assuming no pre-whitening),
>>> but I don't think the variance estimate of Beta_hat_0 the same as
>>> the variance of the signal. oh, well...
>>>
>>>
>>> -Luis
>>>
>>>
>>>
>>>
>>> On Jun 23, 2009, at 10:59 AM, Mark Jenkinson wrote:
>>>
>>>> Hi,
>>>>
>>>> If you are talking about the mean signal as the baseline
>>>> regressor then
>>>> I'm afraid the answer is no. We do not remove the mean signal
>>>> via a
>>>> regressor, but instead remove it from the signal and the model in
>>>> the
>>>> pre-statistical filtering. Hence we do not generate values or
>>>> variances
>>>> for it. But it is easy to calculate the mean using fslmaths and -
>>>> Tmean
>>>> on the original data if that is all you want.
>>>>
>>>> All the best,
>>>> Mark
>>>>
>>>>
>>>> On 23 Jun 2009, at 15:49, Luis Hernandez wrote:
>>>>
>>>>> Dear FSL experts,
>>>>>
>>>>> Is there a way to get FSL to dump the parameter estimate for the
>>>>> baseline regressor into a file, like pe0? (It looks like the
>>>>> mean_func file might do the trick ... is this right?) BUT more
>>>>> importantly, how about its variance estimate? can that be dumped
>>>>> out? FEAT writes out varcope files based on the specified
>>>>> contrasts but I don't see how to make a contrast that uses the
>>>>> baseline regressor, since it is kind of "hidden" ?
>>>>>
>>>>> I apologize if I missed something obvious. thanks in advance
>>>>>
>>>>> -Luis
>>>>>
>>>>> --
>>>>> ( http://www.eecs.umich.edu/~hernan )
>>>>>
>>>>
>>>>
>>>
>>> --
>>> ( http://www.eecs.umich.edu/~hernan )
>>>
>>
>>
>
> --
> ( http://www.eecs.umich.edu/~hernan )
>
---------------------------------------------------------------------------
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
---------------------------------------------------------------------------
|