[FieldTrip] group average over time frequency analysis

philip Joadavi p.joadavi at gmail.com
Sun Mar 6 12:24:41 CET 2022


Dear Tzvetan,

Thanks for your reply. sorry I made a mistake in typing. I meant the
function  FT_FREQGRANDAVERAGE  (time-frequency spectrum
 over multiple subjects). I want to average the time-*frequency* spectrum
over 11 subjects. For averaging, I want to be sure if the function
normalizes the power spectrum for each subject before averaging (to prevent
the influence of one subject on the mean value).
do you know if the function (ft_*freq*grandaverage) does this, or is there
another function that I need to use for normalizing the time-frequency
spectrum for each subject separately?

Thanks a lot!
Philip



On Fri, Mar 4, 2022 at 5:26 PM Tzvetan Popov <tzvetan.popov at uni-konstanz.de>
wrote:

> Dear Philip,
>
> The average over subjects is done by ft_timelockgrandaverage. Possible
> configuration option is  cfg.normalizevar = 'N' or 'N-1' (default = 'N-1’).
> You might consult the help of this function by typing help
> ft_timelockgrandaverage into the command window.
> If by ‘normalisation’ you mean some sort of baseline correction, you
> should apply ft_timelockbaseline for each participant prior to the average
> over participants.
> Good luck,
> tzvetan
>
>
>
> On 4 Mar 2022, at 16:44, philip Joadavi via fieldtrip <
> fieldtrip at science.ru.nl> wrote:
>
> Hi all,
>
> I have a short question for ft_grandaverage. I want to get the average of
> time frequency results over my subjects, and I was wondering if the
> function ft_grandaverage does do the normalization over *subjects* when
> it gets the mean value, or do we need to do the subject normalization
> separately before calling this function?
>
> Thanks a lot!
> Philip
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> https://doi.org/10.1371/journal.pcbi.1002202
>
>
>
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