Hi,
well, this is truly beyond my reach. I cannot tell why your results
might be insignificant. Might be due to an error in the analysis,
might be due to a lack of power, or might be just because there is no
effect. I would advise you to get back to your supervisor and ask for
local help.
When you say you have 14 people: is that a single population, or do
you have two groups you want to compare adding up to a total of 14
people? And finally (excuse me for asking): are you sure you know what
dual regression is doing for you?
All the best,
Cornelius
On Thu, Jul 7, 2011 at 12:48 PM, Rosalia Dacosta Aguayo
<[log in to unmask]> wrote:
>
> Hello Cornelius,
>
> I have gotten only one cluster,...is insignificant....but I only have a
> sample of 14 subjects....what can I do? I have to present my work of Master
> and I would like doing correlations.....
>
> Correlations with FSL or with SPSS?
>
> I am really decepcionated and lost....
>
> Could you help me or give me and advice?
>
> Thanks.
>
> Rosalia.
> 2011/7/7 Rosalia Dacosta Aguayo <[log in to unmask]>
>>
>> Hi Cornelius!
>>
>> Done it!!
>>
>> Cluster, mask of results and activation values!! only with corrp data.
>>
>> Thank you very much!
>>
>> Keep in touch, please.
>>
>> Rosalia.
>>
>> 2011/7/7 Cornelius Werner <[log in to unmask]>
>>>
>>> Hi,
>>>
>>> there might be a typo (oooo vs 0000, for example). Don't copy my exact
>>> term, look inside your directory how the files are called (or get some
>>> local help with someone proficient at shell commands).
>>> Cheers,
>>> Cornelius
>>>
>>> On Thu, Jul 7, 2011 at 10:51 AM, Rosalia Dacosta Aguayo
>>> <[log in to unmask]> wrote:
>>> >
>>> > Hi Cornelius,
>>> >
>>> > I have a problem:
>>> >
>>> > report_DMNP]$ cluster -i dr_stage3_icoooo_tfce_corrp_stat1 -t 0.949 -o
>>> > clustered_image_dr_stage3_ic0000_tstat1.nii.gz
>>> > ** ERROR (nifti_image_read): failed to find header file for
>>> > 'dr_stage3_icoooo_tfce_corrp_stat1'
>>> > ** ERROR: nifti_image_open(dr_stage3_icoooo_tfce_corrp_stat1): bad
>>> > header
>>> > info
>>> > Error: failed to open file dr_stage3_icoooo_tfce_corrp_stat1
>>> > Cannot open volume dr_stage3_icoooo_tfce_corrp_stat1 for reading!
>>> > [neuropsico1@UB16-336-161116099027 report_DMNP]$
>>> >
>>> > 2011/7/7 Cornelius Werner <[log in to unmask]>
>>> >>
>>> >> Hi,
>>> >>
>>> >> an uncorrected threshold of 0.01 will yield too many false-positives,
>>> >> in my opinion. If none of the uncorrected differences survive
>>> >> correction for multiple testing, then that's a fact. I would not try
>>> >> and force the matter unnecessarily. For the underlying final
>>> >> statistics, familiarize yourself with the "randomise" command. The
>>> >> dual_regression script itlself is also not too complicated for someone
>>> >> apt at shell scripting.
>>> >>
>>> >> To get the cluster statistics:
>>> >> type "cluster -i dr_stage3_ic00001_corrp_tstat1 -t 0.949 -o
>>> >> clustered_image_ic00001.nii.gz"
>>> >> This produces an image containing only clusters significant at p<0.05
>>> >> corrected for component 2 (!) of the web page report
>>> >> (ic00000=component 1, ic00001=component 2 and so on).
>>> >> To get images containing only single clusters type "fslmaths
>>> >> clustered_image_ic00001.nii.gz -thr 1 -uthr 1
>>> >> cluster1_image_ic00001.nii.gz" for cluster number 1, "fslmaths
>>> >> clustered_image_ic00001.nii.gz -thr 2 -uthr 2
>>> >> cluster2_image_ic00001.nii.gz" and so forth. Hope that helps.
>>> >>
>>> >> Best wishes,
>>> >> Cornelius
>>> >>
>>> >> On Wed, Jul 6, 2011 at 7:07 PM, Rosalia Dacosta Aguayo
>>> >> <[log in to unmask]> wrote:
>>> >> > Yes, Cornelius,
>>> >> > But I have differences with all my networks with uncorrected data,
>>> >> > and I
>>> >> > would like including them to see what happens...with a threshold of
>>> >> > 0.99, I
>>> >> > think it's good, but I don't know if it's generally accepted in the
>>> >> > literature. And, I don't know how to do this...I have been reading
>>> >> > Randomise but I am just a begginer and in another language I have
>>> >> > arrived to
>>> >> > do dual_regression...but I need some more helping. Could you help
>>> >> > me,
>>> >> > please?
>>> >> >
>>> >> > Best regards,
>>> >> > Rosala.
>>> >> > 2011/7/6 Cornelius Werner <[log in to unmask]>
>>> >> >>
>>> >> >> If you have run an unmodified version of the script, the "corrp"
>>> >> >> output IS already cluster thresholded (using TFCE) corrected for
>>> >> >> multiple comparisons. That's why it is called "corrp" = corrected
>>> >> >> p.
>>> >> >> TFCE has the advantage that no a priory cluster forming threshold
>>> >> >> needs to be specified, and it is quite sensitive. If you took the
>>> >> >> notion of correcting for multiple testing really seriously, you
>>> >> >> probably needed to divide your p-value by the number of components
>>> >> >> and
>>> >> >> the number of directional tests for each component...Therefore,
>>> >> >> there
>>> >> >> is no need (and probably no use) in cluster correcting the
>>> >> >> uncorrected
>>> >> >> data. You could apply a FDR correction, however. See the online
>>> >> >> manual
>>> >> >> on how to do it. On a side note: it is not expected for every map
>>> >> >> to
>>> >> >> behave differentially across groups.
>>> >> >>
>>> >> >> Cheers,
>>> >> >> Cornelius
>>> >> >>
>>> >> >> On Wed, Jul 6, 2011 at 6:30 PM, Rosalia Dacosta Aguayo
>>> >> >> <[log in to unmask]> wrote:
>>> >> >> > Hi,
>>> >> >> > I have done dual_regression and I have seen with fslview
>>> >> >> > dr_stage3
>>> >> >> > corrp_stat1 and 2 and pstat1 and 2.
>>> >> >> > I have seen that with a threshold of 0.95 (corrp_stat1 and 2)
>>> >> >> > with
>>> >> >> > only
>>> >> >> > 14
>>> >> >> > subjects I have ssen activation in only two or three networks.
>>> >> >> > But,
>>> >> >> > with
>>> >> >> > pstats1 and 2, with a threshold of 0.99, all my components show
>>> >> >> > activation
>>> >> >> > in the different networks. Now, I have to do the clustering, but
>>> >> >> > I
>>> >> >> > don't
>>> >> >> > know how to do it...someone could help me, please?
>>> >> >> > Thank you.
>>> >> >> > Rosalia.
>>> >> >>
>>> >> >>
>>> >> >>
>>> >> >> --
>>> >> >> Dr. med. Cornelius J. Werner
>>> >> >> Department of Neurology
>>> >> >> RWTH Aachen University
>>> >> >> Pauwelsstr. 30
>>> >> >> 52074 Aachen
>>> >> >> Germany
>>> >> >
>>> >> >
>>> >>
>>> >>
>>> >>
>>> >> --
>>> >> Dr. med. Cornelius J. Werner
>>> >> Department of Neurology
>>> >> RWTH Aachen University
>>> >> Pauwelsstr. 30
>>> >> 52074 Aachen
>>> >> Germany
>>> >
>>> >
>>>
>>>
>>>
>>> --
>>> Dr. med. Cornelius J. Werner
>>> Department of Neurology
>>> RWTH Aachen University
>>> Pauwelsstr. 30
>>> 52074 Aachen
>>> Germany
>>
>
>
--
Dr. med. Cornelius J. Werner
Department of Neurology
RWTH Aachen University
Pauwelsstr. 30
52074 Aachen
Germany
|
