[FieldTrip] grandaveraging EEG question

[Raquel Bibi]

Hi Dave
I would think that appending the data would weigh each subject by the number of trials, something that isn't done when we use timelock_grandaverage. 

Best,

Raquel

Sent from my iPhone

> On Apr 5, 2014, at 4:20 PM, "Herring, J.D. (Jim)" <j.herring at fcdonders.ru.nl> wrote:
> 
> Hi Dave,
> 
> I would read in, and preprocess, the two files per subject and run ft_appenddata to combine the data from both files. Then I would run ft_timelockanalysis to get the erps for each condition. As soon as you have done this for all subjects, run ft_timelockgrandaverage to get the group averaged erps.
> 
> Best,
> 
> Jim
> 
>> On 4 apr. 2014, at 19:38, Dave Britton <dave at davebritton.com> wrote:
>> 
>> I have EEG data that consist of two separate file sets for each subject, and 20 subjects. When I process this to get ERPs for various conditions, does it matter if I just use ft_appenddata to concatenate all 40 files together and then run ft_timelockanalysis on the result, or should I use ft_grandaverage to combine the two runs for each subject, using the "within" parameter" and then combine the 20 resulting grandaverages with another call to ft_grandaverage using the "between parameter?
>> -Dave
>> _______________________________________________
>> fieldtrip mailing list
>> fieldtrip at donders.ru.nl
>> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip
> 
> _______________________________________________
> fieldtrip mailing list
> fieldtrip at donders.ru.nl
> http://mailman.science.ru.nl/mailman/listinfo/fieldtrip