<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Dear Mehmet,<div class=""><br class=""></div><div class="">Since you have 19 channels for which you do the test, you have the multiple comparison problem. That means that you are not controlling for the false alarm rate: with more channels, the chances are increasing that one of the channels will have a false alarm and that yu will therefore make the incorrect decision of rejecting your null hypothesis.</div><div class=""><br class=""></div><div class="">A permutation-based nonparametric test using clustering corrects for multiple comparisons. An independent sample t-test does in general not correct for multiple comparisons, unless you adjust the critical value (i.e. Bonferoni correction). </div><div class=""><br class=""></div><div class="">If you have 19 channels, you can do the t-test with an alpha level of 5% divided by 19, i.e. 0.2632% </div><div class=""><br class=""></div><div class="">best regards,</div><div class="">Robert</div><div class=""><br class=""></div><div class="">PS please follow up questions like these on the <a href="http://fieldtriptoolbox.org/discussion_list" class="">http://fieldtriptoolbox.org/discussion_list</a>, to which I have also CCed this answer</div><div class=""><br class=""></div><div class=""><br class=""><div><br class=""><blockquote type="cite" class=""><div class="">On 6 Aug 2018, at 17:41, Mehmet Akif Özçoban <<a href="mailto:mehmetakifozcoban@gmail.com" class="">mehmetakifozcoban@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div dir="ltr" class=""><div style="font-family:monospace,monospace;font-size:large;color:rgb(0,0,255)" class="gmail_default">
<div class="gmail_default">Dear professor, I want to ask you about a problem, please could you help me. <br class=""></div><div class="gmail_default"><br class=""></div><div class="gmail_default">I am working obsessive compulsive disorder and i have 30 patient and 30 helathy control data. <br class=""></div><div class="gmail_default"><br class=""></div><div class="gmail_default">I compute synchronization value of each channel and compared with using independent sample t-test. <br class=""></div><div class="gmail_default"><br class=""></div><div class="gmail_default">Some
reviewers advice me that you should not use each channels
synchronization and you should use nonparametric testing of EEG. But I
want to conclude it according to spatial features. I am listening some
lessons and they used it for comparison of two situation not 19
situtaion (synhronization value for channels)<br class=""></div><div class="gmail_default"><br class=""></div><div class="gmail_default">How can i adapt my research your permutation testing statistical method.</div><div class="gmail_default"><br class=""></div><div class="gmail_default">Thank youmy manuscript had been attached. Please can you read for me</div>
</div><br class="">-- <br class=""><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div dir="ltr" class=""><div class=""><font size="4" class=""><span style="color:rgb(204,0,0)" class=""><span style="font-family:garamond,serif" class=""><font style="background-color:rgb(255,255,255)" class=""><span class="">Sincerely<br class=""></span></font></span></span></font></div><div class=""><font size="4" class=""><span style="color:rgb(204,0,0)" class=""><span style="font-family:garamond,serif" class=""><font style="background-color:rgb(255,255,255)" class=""><span class="">Mehmet Akif ÖZÇOBAN</span>, phD<br class=""></font></span></span></font></div><div class=""><font size="4" class=""><span style="color:rgb(204,0,0)" class=""><span style="font-family:garamond,serif" class=""><span style="background-color:rgb(255,255,255)" class=""></span></span></span></font></div><div class=""><font size="4" class=""><span style="color:rgb(204,0,0)" class=""><span style="font-family:garamond,serif" class="">Istanbul Gedik University</span></span></font></div><br class=""></div></div></div></div></div></div></div></div></div>
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