[Eeglablist] How are units in SIFT connectivity outputs created from model coefficients?

[Makoto Miyakoshi]

Dear James,

> how the (unit-less?) SIFT connectivity estimation, specificaly dDTF and
rPDC, are converted to Spectral Density or Decibels.

I don't think it converts dDTF/rPDC measures into decibels. Probably the
decibel conversion is only applied to spectrum density... Can you double
check it?

Makoto

On Thu, Jul 30, 2015 at 11:57 AM, James Jones-Rounds <jj324 at cornell.edu>
wrote:

> Hello all,
>
> Looking thoroughly through the SIFT manual, and related references online,
> I'm having trouble seeing definitively how the (unit-less?) SIFT
> connectivity estimation, specificaly dDTF and rPDC, are converted to
> Spectral Density or Decibels.
>
> Can anyone give a summary, or point to a reference ( if possible, for
> non-mathematicians), that describes a little more about how the final
> output, in the EEG.CAT.Conn fields, results from the coefficients of the
> MVAR model?
>
> We typically check yes to convert spectral density to dB, when running
> SIFT, and I see in the SIFT documentation that the spectral density matrix
> and transfer function are obtained from the autoregressive model
> coefficients. But we really want to be sure of what those final
> (non-unit-less) values represent before we start manipulating them for the
> purposes of group analysis and publication.
>
> Thank you anyone who can provide some insight!
>
> James
>
> --
> James Jones-Rounds
> Laboratory Manager
> Human Development EEG and Psychophysiology (HEP) Laboratory,
> Department of Human Development,
> --------------------------------------------
> Cornell University | Ithaca, NY
> 607-255-9883
> eeg at cornell.edu
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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