[Mne_analysis] Unbalanced number of trials between individuals: problem in sources

[Laetitia Grabot]

So does that mean that we need not to equalize epochs between conditions
(within one subject)?

2016-03-03 16:23 GMT+01:00 Denis-Alexander Engemann <
denis.engemann at gmail.com>:

> Hi Laetitia,
>
> I I'm understanding you correctly this should not be an issue for evoked
> data as long as you are using the .average method that will tell the
> inverse routines how to scale the data via its .nave attribute.
> Did you have any particular problems?
>
> Cheers,
> Denis
>
> On Thu, Mar 3, 2016 at 3:09 PM, Laetitia Grabot <laetitia.grabot at gmail.com
> > wrote:
>
>> Dear MNE-users,
>>
>> I am aware of the fact that when contrasting two conditions, the epochs
>> within each condition should be equalized before reconstructing in source
>> space, otherwise the SNR would be different between the two conditions.
>> That also means that if two subjects have a different number of epochs, the
>> SNR of each subject will be different. It is often the case that the number
>> of epochs doubled between subjects (50 vs. 100) so I guess that it is an
>> issue when looking at group averaged stc for instance.
>> A possible solution would be to normalize the stc to correct for the
>> number of trials. What do you think of that? What would be the proper
>> normalization?
>>
>> Thanks,
>> Best,
>> Laetitia G.
>>
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