[Eeglablist] Baseline in block design

[Cedric Cannard]

Dear Patrick,

The baseline here refers to the pre-stimulus period, not a subject baseline like a some period you would record before starting the actual trials. While it used to be pretty standard to remove baseline before, new guidelines are to avoid it, as it is "statistically unnecessary and even undesirable". See for example: 
https://urldefense.com/v3/__https://www.nature.com/articles/s41598-023-27528-0__;!!Mih3wA!HslNgUeGGgB1MvOMbw5UdRXh4UNEpurRZ_QVOWqXDjPszAY-Iw_y6N9_9GBAibHH7vu_gcwm26z-wlkSVwxt_XrPiQ$ 
https://urldefense.com/v3/__https://onlinelibrary.wiley.com/doi/abs/10.1111/psyp.13451__;!!Mih3wA!HslNgUeGGgB1MvOMbw5UdRXh4UNEpurRZ_QVOWqXDjPszAY-Iw_y6N9_9GBAibHH7vu_gcwm26z-wlkSVwzzpqOXhg$ 

Simply apply a highpass filter (e.g. 0.5 or 1 Hz) instead to remove low frequency DC drifts. 

Cedric



------- Original Message -------
On Tuesday, April 11th, 2023 at 5:22 PM, patrick bedard via eeglablist <eeglablist at sccn.ucsd.edu> wrote:


> Hi everyone
> 
> I'm quite new at EEG analysis.
> I have a block design 30 sec ON, 30 sec OFF, starting with ON, in 2 groups
> (controls, patients).
> It's a fatigue paradigm so performance changes rapidly from block to block
> (within blocks too, but that's for another day!!).
> I want to compare between groups for each block using time-frequency I
> computed with discrete FFT at each second (30 datapoints per block).
> 
> My question is about the baseline. I don't think I have one since the exp
> started with the ON condition. And it seems it's important to remove the
> baseline in EEG analysis.
> Is it in my contextI
> Do I need to compute and remove a baseline from the ON blocks to be able to
> interpret them correctly?
> Can't I just compare the 2 groups directly at each block?
> 
> thanks in advance for your time
> pat
> 
> ------------------------------------
> Patrick Bédard
> Researcher
> National Institutes of Health
> 401-270-5361
> _______________________________________________
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to eeglablist-request at sccn.ucsd.edu