[Eeglablist] ERSP

[Makoto Miyakoshi]

Dear Konstantina,

I understand! This is the most frequently repeated question.

> For me it seems logical to use the range that i computed ERP...

Ok let me tell you the logic here.
To compute ERSP, a sliding window is used. If the sliding window length is
301 points, you'll lose the first 150 and the last 150 datapoints from your
epoch, because one 301-point-long window does not generate 301 data points
as results, but it generates only 1 data point to return. See slide 21 of
this pdf file.
https://sccn.ucsd.edu/mediawiki/images/a/a6/C2_A3_Time-frequencyDecAndAdvancedICAPracticum_updateJan2017.pdf

So, if you want ERPS to have the same length as your ERP, you have to add
half window length to both of your epoch ends to extend your epoch (which
will make your ERP longer as a result; so you have to 'shroten' ERP to the
length of ERSP to match their lengths.)

Makoto

On Mon, Jul 16, 2018 at 9:55 PM Konstantina Tsekoura <tsekou at ceid.upatras.gr>
wrote:

> Hello,
>
> i am confused about time limits in newtimef...
> I found that epochlim must be the whole epoch:
>
>   epochlim    = [mintime maxtime] (ms).  Note that these are the time
> limits
> %                     of the data epochs themselves, NOT A SUB-WINDOW TO
> EXTRACT
> %                     FROM THE EPOCHS as is the case for pop_newtimef().
> {[-1000 2000]}
>
>
>
> In my study i am computing ERP with time limits [-400 1990] while my
> epoch is [-1000 2000]. And now i would like to compute with newtimef
> ERSP from ERP... do i have to use [-1000 2000] to epochlim or [-400
> 1990]?
>
> For me it seems logical to use the range that i computed ERP...
>
> I would appreciated if anyone could help me...
>
> Thank you,
> Konstantina
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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