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exlcuding channels


Nicollette Purcell
Posts: 20
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(@nicopurc88)
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Hi All,

I have a question about what is happening when I chose channels to exclude from analysis. For one of my subjects I had to exclude quite a few bad channels (that resulted from a cap issue) which I did by left-clicking those channels in the probe window. However, when I export the HRF for the subject there is still data in the columns of all of the excluded channels. Does this mean even channels that I chose to exclude are still used in both individual and group HRF calculations? Or am I just doing something wrong/misunderstanding this function? Any help is appreciated

Nicollette

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Stephen Tucker
Posts: 42
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Hi,

 

The excluded channels should be excluded from propagating to subject and group level averages/analysis.

 

They are not excluded from tCCA analysis yet, unfortunately (I may be mistaken)

 

Channel exclusion is unfortunately not a totally mature feature so if you sense that data is being improperly included in your subject level block averages, for instance, let us know.

I will try to prioritize polishing up this feature if it proves to be useful to users

 

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Nicollette Purcell
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Joined: 1 year ago

Posts: 20

Hi Stephen,

Thanks for getting back to me. I attached an individual's HRF file as an example. Within Homer's plot window I manually excluded channels 10,7 and 9,7 for the 'F' stim mark. However, there are still values for these columns which makes me concerned these channels were included in the group analyses as well. My main concern is that these garbage channels are skewing the group averages and I don't know how to tell if they are, in fact, being included in the group analysis. If you have any further advice on how to proceed, I'd greatly appreciate it.

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David Boas
Posts: 125
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Yeah, pruning channels should be verified. It should prevent those channels from impacting analyses of other channels and from propagating into averages across runs for a subject, and averages across subjects for a group. But it hasn't pevented the block average or GLM function from calculating their HRFs as this has no negative impact on the higher level results and allows the user to inspect their result.

We should definitely check that the new tCCA function follows this behavior as well.

 

 

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Nicollette Purcell
Posts: 20
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(@nicopurc88)
Joined: 1 year ago

Hi @dboas, At the moment I was just trying to manually exclude channels from the block average so they are not incorporated at the subject or group level analysis. However, the channels I marked to be excluded in the probe window are still in the subject's exported HRF file and seemingly in the group analysis too. Do you have an idea of how I can remedy this? I did my own group averaging as to not include the bad channels for some prelim analyses, but I'm hoping to be able to use the function in the future as my number of participants increases. Any help is appreciated.

 

Nicollette

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