[FieldTrip] Nonparametric statistical testing of phase coherence

[Ana Navarro Cebrian]

Thank you, Eric. Would then make sense to add all the trials (from all subjects) from condition1 in one set, and all the trials (from all subjects) from condition2 in a second set, and run this Montecarlo simulation (the same way I was talking about to compare) those two conditions?Thanks again,Ana


  

From: e.maris at psych.ru.nl
To: fieldtrip at science.ru.nl
Date: Wed, 10 Apr 2013 09:21:28 +0200
Subject: Re: [FieldTrip] Nonparametric statistical testing of phase coherence

Hi Ana, Yes, this is correct. Eric Maris From: Ana Navarro Cebrian [mailto:sabato45 at hotmail.com] 
Sent: dinsdag 9 april 2013 19:57
To: FieldTrip discussion list
Subject: Re: [FieldTrip] Nonparametric statistical testing of phase coherence Hi Maris,thank you for your response.I think my question wasn't clear. Let me rephrase it. I'd like to apply the montecarlo approach that you explain in Maris et al., because I havetwo conditions (errors vs correct responses) with a huge difference in the number of trials. In this case, I understand that I have to apply the montercarlo simulationacross trials to find out whether condition 1 is different from condition 2 independently of their different number of trials.If that's correct, my question is, do I get a p-value from this procedure? If so, after performing the same analysis for each subject independently, I'll end up with a p-value for each subject. Is that correct? I'm sorry if I'm not understanding something basic.I really appreciate your help.Ana     From: e.maris at psych.ru.nl
To: fieldtrip at science.ru.nl
Date: Tue, 9 Apr 2013 12:09:03 +0200
Subject: Re: [FieldTrip] Nonparametric statistical testing of phase coherenceHi Ana, To compare coherence between conditions across subjects (instead of trials), you need a different statfun: depsamplesT (for a within-subjects design; subjects have participated in all conditions) or indepsamplesT  (for a between-subjects design; subjects have participated in only one condition). Typically, this type of test is performed using power as the dependent variable, but exactly the same test is used for comparing coherence in a multiple-subject study. However, you will have to specify the cfg.parameter field when calling ft_freqstatistics such that it points to the data field that contains your coherence data (importantly, for a given reference channel). Good luck, Eric Maris  From: Ana Navarro Cebrian [mailto:sabato45 at hotmail.com] 
Sent: vrijdag 5 april 2013 23:56
To: fieldtrip at science.ru.nl
Subject: [FieldTrip] Nonparametric statistical testing of phase coherence 
Hello everybody,I'd like to use the test proposed in Maris et al., 2007 (that I believe is implemented in statistics_montecarlo.m?). I'm calculating the difference in phase coherence between two conditions. The problem is that one condition has much less trials than the other, so I imagine the Montecarlo simulation would need to be across trials, in which case, I'd end up with a p-value for each individual subject, right? I'm not sure then how to apply this across subjects. The Maris et al. paper is very clear, but it only explains single subject analysis. I hope that makes any sense. I appreciate any help.Thanks,Ana  
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