[Mne_analysis] equivalence of averaged single trial STCs and evoked STCs

[dgw]

Hi Tal,

at least for the MNE, nave has no influence. For the dSPM it will, though depending on the purpose, I would lean towards sticking with the MNE.

Off the top of my head, I'm not sure of the implications in the math of using the dSPM (and messing with the nave).

Anybody have a good idea for the dSPM?

D

On Mar 15, 2014, at 4:17 PM, Tal Linzen wrote:

> Thanks. So just to make sure I understand what this all means, what is the recommended nave value for a single trial source solution, assuming we want to later average the single trial activations and get something similar to applying the inverse operator to averaged epochs? And what is the implication of what you're saying for choosing dSPM or MNE in a single trial analysis?
> 
> Thanks,
> Tal
> 
> 
> On Sat, Mar 15, 2014 at 3:58 PM, Alexandre Gramfort <alexandre.gramfort at telecom-paristech.fr> wrote:
> > Also, just wanted to quickly add that in my understanding, what dSPM is
> > essentially trying to achieve is the same kind of normalization as would
> > result when you do MNE first and then scale by the baseline..
> 
> it's the same objective but it's mathematically different.
> 
> one more thing to add is that the nave also plays a role
> in the scaling of the regularization parameter. It scales the noise
> cov used in dSPM but it's not a plain scaling
> of the estimates.
> 
> Alex
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