<div dir="ltr">Hi,<div><br></div><div>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.</div>
<div><br></div><div>Cheers,</div><div>Hweeling</div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On 17 July 2014 16:43, "Jörn M. Horschig" <span dir="ltr"><<a href="mailto:jm.horschig@donders.ru.nl" target="_blank">jm.horschig@donders.ru.nl</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hey,<br>
<br>
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... ;)<br>
<br>
Best,<br>
Jörn<div class=""><br>
<br>
<br>
On 7/17/2014 3:45 PM, Constantino Méndez Bértolo wrote:<br>
</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="">
Bump,<br>
wishing that some sage fieldtripper either back-up the "t-test against homologue data filled with zeros method" or suggests a better approach,<br>
thx<br>
<br>
<br></div>
2014-07-17 13:56 GMT+02:00 Lam, Nietzsche <<a href="mailto:n.lam@fcdonders.ru.nl" target="_blank">n.lam@fcdonders.ru.nl</a> <mailto:<a href="mailto:n.lam@fcdonders.ru.nl" target="_blank">n.lam@fcdonders.ru.nl</a>><u></u>>:<div class="">
<br>
<br>
Hi Hweeling,<br>
<br>
I think the approach is similar to testing two different<br>
conditions. I have a suggestion below, but I think some people<br>
would argue that this is not a good way to do the test.<br>
<br>
You can keep the design matrix the same as comparing two<br>
conditions, but for the "zero" condition, you will turn this all<br>
into zeros.<br>
dat1.powspctrm = %power from your condition of interest<br>
dat2 = dat1 % your "zero" condition"<br>
dat2.powspctrm(:) = 0; % making the data structure identical to<br>
condition of interest but everything is zero.<br>
Then call your statistics function as before.<br>
<br>
Perhaps someone else can give you more detail on this.<br>
<br>
Nietzsche<br>
<br>
----- Original Message -----<br>
> From: "Hwee Ling Lee" <<a href="mailto:hweeling.lee@gmail.com" target="_blank">hweeling.lee@gmail.com</a><br></div><div class="">
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> Sent: Thursday, 17 July, 2014 1:26:59 PM<br>
> Subject: [FieldTrip] testing if power is significantly different<br>
from zero<br>
> Hi all,<br>
><br>
><br>
> I have a naive question regarding cluster statistics in fieldtrip.<br>
><br>
><br>
> Is it possible to run a statistical analysis to test if power is<br>
> significantly different from zero? If so, how do I build the design<br>
> matrix for this case?<br>
><br>
><br>
> Thanks.<br>
><br>
><br>
> Cheers,<br>
> Hweeling<br>
><br>
><br>
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<br>
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Jörn M. Horschig<br>
PhD Student<div class=""><br>
Donders Institute for Brain, Cognition and Behaviour<br></div>
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Radboud University Nijmegen<br>
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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div dir="ltr">=================================================<br>Dr. rer. nat. Lee, Hwee Ling<br>Postdoc<br>German Center for Neurodegenerative Diseases (DZNE) Bonn<br>
<br>Email 1: hwee-ling.lee<at><a href="http://dzne.de" target="_blank">dzne.de</a><br>Email 2: hweeling.lee<at><a href="http://gmail.com" target="_blank">gmail.com</a><div><br></div><div><a href="https://sites.google.com/site/hweelinglee/home" target="_blank">https://sites.google.com/site/hweelinglee/home</a><br>
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