[Eeglablist] Why are power values different when a single channel is plotted vs multiple channels?

[Makoto Miyakoshi]

Dear Gan and Mikolaj,

I think Mikolaj is correct. spectopo() takes 2D data as input and does not
take event structures, so most likely it does not take boundary into
consideration. pop_spectopo() detects 'boundary'.

Makoto

2013/3/17 Mikołaj Magnuski <imponderabilion at gmail.com>

> Ah, right, it is possible that only one of these functions respects
> 'boundary' events,
> so the other one generates different spectrum due to discontinuities in
> the signal.
> Unfortunately, I do not remember which one is more careful about
> boundaries,
> my guess is that pop_spectopo, passes 'boundary' latencies to spectopo
> 'boundaries' property so they are respected.
> But Makoto or Arno should give you a more definite answer.
>
>
> Pozdrawiam,
> Mikołaj Magnuski
>
>
> 2013/3/17 Gan, Hock <h.c.gan at herts.ac.uk>
>
> The percent data tha I use is always 100%. I believe the discrepancy is
>> due to manual rejection of artefacts which introduces boundaries of
>> discontinuities. To enter these in the single channel case would be quite a
>> task. I'm interested in what sort of processing differentiates the
>> processing of boundaries.
>>
>> Thanks,
>> Hock
>> ________________________________________
>> From: Mikołaj Magnuski [imponderabilion at gmail.com]
>> Sent: 17 March 2013 11:31
>> To: Gan, Hock; eeglablist at sccn.ucsd.edu
>> Subject: Re: Why are power values different when a single channel is
>> plotted vs multiple channels?
>>
>> Hey,
>>
>> make sure that in 'channel spectra and properties'
>> the chosen 'percent of data to sample' is 100
>> Otherwise running 'channel spectra and properties'
>> twice can give you different results (but is faster).
>>
>>
>> Mikołaj
>>
>
>
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-- 
Makoto Miyakoshi
JSPS Postdoctral Fellow for Research Abroad
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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