[FieldTrip] testing if power is significantly different from zero

[Hwee Ling Lee]

Hi,

Thanks for all the input. The reason I wanted to test if power is
significantly different from 0 is to check if the power in condition 1
resembles to what is reported in the literature. This is just to ensure
that the changes observed in condition 2 relative to condition 1 makes
sense.

Cheers,
Hweeling



On 17 July 2014 16:43, "Jörn M. Horschig" <jm.horschig at donders.ru.nl> wrote:

> Hey,
>
> I actually wouldn't advise to test power against 0. Since power is a
> positive measure (bound to 0), noise will cumulatatively add up and your
> test against 0 will effectively check whether you recorded something (aka
> noise) or not. But, as Nietzsche said, you can ask whether your measured
> powered is significantly different from 0 using her approach. It's just not
> a very clever question to ask... ;)
>
> Best,
> Jörn
>
>
>
> On 7/17/2014 3:45 PM, Constantino Méndez Bértolo wrote:
>
>> Bump,
>> wishing that some sage fieldtripper either back-up the "t-test against
>> homologue data filled with zeros method" or suggests a better approach,
>> thx
>>
>>
>> 2014-07-17 13:56 GMT+02:00 Lam, Nietzsche <n.lam at fcdonders.ru.nl <mailto:
>> n.lam at fcdonders.ru.nl>>:
>>
>>
>>     Hi Hweeling,
>>
>>     I think the approach is similar to testing two different
>>     conditions. I have a suggestion below, but I think some people
>>     would argue that this is not a good way to do the test.
>>
>>      You can keep the design matrix the same as comparing two
>>     conditions, but for the "zero" condition, you will turn this all
>>     into zeros.
>>     dat1.powspctrm = %power from your condition of interest
>>     dat2 = dat1      % your "zero" condition"
>>     dat2.powspctrm(:) = 0; % making the data structure identical to
>>     condition of interest but everything is zero.
>>     Then call your statistics function as before.
>>
>>     Perhaps someone else can give you more detail on this.
>>
>>     Nietzsche
>>
>>     ----- Original Message -----
>>     > From: "Hwee Ling Lee" <hweeling.lee at gmail.com
>>     <mailto:hweeling.lee at gmail.com>>
>>     > To: "FieldTrip discussion list" <fieldtrip at science.ru.nl
>>     <mailto:fieldtrip at science.ru.nl>>
>>     > Sent: Thursday, 17 July, 2014 1:26:59 PM
>>     > Subject: [FieldTrip] testing if power is significantly different
>>     from zero
>>     > Hi all,
>>     >
>>     >
>>     > I have a naive question regarding cluster statistics in fieldtrip.
>>     >
>>     >
>>     > Is it possible to run a statistical analysis to test if power is
>>     > significantly different from zero? If so, how do I build the design
>>     > matrix for this case?
>>     >
>>     >
>>     > Thanks.
>>     >
>>     >
>>     > Cheers,
>>     > Hweeling
>>     >
>>     >
>>     > _______________________________________________
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>>
>>     > http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>>
>>     --
>>     Nietzsche H.L. Lam, MSc
>>     PhD Candidate
>>
>>     Max Planck Institute for Psycholinguistics
>>     Wundtlaan 1, 6525 XD Nijmegen, The Netherlands
>>
>>     Donders Institute for Brain, Cognition and Behaviour,
>>     Centre for Cognitive Neuroimaging,
>>     Kapittelweg 29, 6525EN Nijmegen, The Netherlands
>>
>>     n.lam at fcdonders.ru.nl <mailto:n.lam at fcdonders.ru.nl>
>>     +31-24-3668219 <tel:%2B31-24-3668219>
>>
>>
>>     neurobiologyoflanguage.com <http://neurobiologyoflanguage.com>
>>     _______________________________________________
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>>
>>     http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
>>
>>
>>
>>
>> --
>> Constantino Méndez-Bértolo
>> Laboratorio de Neurociencia Clínica,Centro de Tecnología Biomédica (CTB)
>>
>>
>> Parque Científico y Tecnológico de la UPM, Campus de Montegancedo
>>
>> 28223 Pozuelo deAlarcón, Madrid, SPAIN
>>
>>
>>
>>
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>>
>
>
> --
> Jörn M. Horschig
> PhD Student
>
> Donders Institute for Brain, Cognition and Behaviour
> Centre for Cognitive Neuroimaging
> Radboud University Nijmegen
> Neuronal Oscillations Group
> FieldTrip Development Team
>
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>
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-- 
=================================================
Dr. rer. nat. Lee, Hwee Ling
Postdoc
German Center for Neurodegenerative Diseases (DZNE) Bonn

Email 1: hwee-ling.lee<at>dzne.de
Email 2: hweeling.lee<at>gmail.com

https://sites.google.com/site/hweelinglee/home

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