[FieldTrip] creating difference wave
xianwei.che at monash.edu
Thu Sep 22 08:31:14 CEST 2016
Here is my understanding of this.
The field ".avg" is in the output of timelockanalysis, which is the average
across the trials. But in the output of freqanalysis there is no ".avg"
field as the field "powspctrm " is the "averaged" results.
So, if I want to create a difference wave of the freqanalysis between two
conditions; I just use the ft_math to subtract the field "powspctrm" in one
condition from the other one.
I don't know if this is right; any suggestion would be appreciated.
*Mr Xianwei Che*
*Monash Alfred Psychiatry Research Centre (MAPrc)*
*Central Clinical School & the Alfred *
*Level 4, 607 St Kilda Road, Melbourne **3004, **Australia*
On 22 September 2016 at 14:26, Xianwei Che <xianwei.che at monash.edu> wrote:
> Dear list,
> I have some concerns of how to create difference wave between two
> conditions. Here is what I want to look at:
> I have grand average time-freqency data of two conditions ("GA1","GA2"),
> and one behavioural measurement. Now I want to do so some
> regression/correlation analysis between the behavioural measurement and the
> contrasted time-freqency data (GA1-GA2).
> I did some googling and it is suggested to create the difference wave
> first, as per here (http://www.fieldtriptoolbox.o
> From these 4 data structures, you now make 2 difference data structures in
> the following way:
> - Copy GA11 to GAdiff11_12 and perform the assignment
> - Copy GA21 to GAdiff21_22 and perform the assignment
> I got confused about the '.avg' here. Powspctrm is 4-d data in each GA
> (subject.channel.frequency.time); so what is and how to calculate the
> average (.avg) in each GA structure.
> Or is it just a filed in each GA as I cannot find one.
> Thanks a lot
> *Mr Xianwei Che*
> *PhD Candidate*
> *Monash Alfred Psychiatry Research Centre (MAPrc)*
> *Central Clinical School & the Alfred *
> *Monash University*
> *Level 4, 607 St Kilda Road, Melbourne **3004, **Australia*
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