[Eeglablist] Setting the significance level for the ERSPs. How it works?

Max Cantor Max.Cantor at colorado.edu
Thu Nov 9 10:53:22 PST 2017


My understanding is that a baseline of NaN means that there is no baseline,
whereas an empty baseline value uses the average as a baseline. This
baselining, however, is independent of the bootstrapping. If you are not
inputting a baseline vector into bootstat, then I believe it just tests the
ERSP against an average baseline. I've been calling bootstat directly,
outside of the GUI/pop_newtimef or newtimef, so I don't know off hand if it
is possible to add this baseline vector to bootstat as an input in the GUI
/ pop_newtimef / newtimef. I've been asking several questions about ERSP
statistics myself, so if you search for my question on the mailing list, my
thought process and the comments I've received may be helpful. That being
said, I am also in the process of trying to understand things, so don't
take what I'm saying as the end-all-be-all.

If I am interpreting things correctly, I think that it does not matter per
se how you've baselined the ERSP prior to running the bootstrap statistic,
so long as it makes sense for what you are trying to do- in other words, I
think that's just an empirical or theoretical question. Likewise, whether
the bootstrap statistic should be tested against an average baseline or a
specific window of the ERSP seems like an empirical/theoretical question to
me.

I guess the long and short of it is to make sure you are doing whatever
makes the most empirical or theoretical sense for you, and that how you
baseline the ERSP is separate from what baseline you use to statistically
test against your ERSP.

Best,
Max

On Mon, Nov 6, 2017 at 2:03 PM, Tarik S Bel-Bahar <tarikbelbahar at gmail.com>
wrote:

> Hello Nabi,
>
> 1. I'm not 100% sure, but the significance levels are probably significant
> compared to the baseline you have set. If you have no baseline set, they
> are probably set to the whole time period. You probably want to play around
> setting the baseline to different settings, in order to get a better feel
> for how the ersp baselining and significance works. If you have not had a
> chance to yet, beginning users can really benefit from working first with
> the eeglab tutorial data, and again playing around with the settings in the
> ersp function gui.
>
> 2. If you have not had a chance to yet, you want to look thoroughly
> through the documentation for the ERSP function (type help or doc and
> Name-of-function in matlab command window, or click the Help button in the
> ersp function window).
>
> 3. When you have a solution, please share it with the list as a followup
> post, so that other list users can benefit from your experiences.
>
>
>
>
>
> On Fri, Nov 3, 2017 at 7:21 AM, Nabi Rustamov <nabi.rustamov at yahoo.com>
> wrote:
>
>> Hello
>>
>> Can you please let me know how setting the significance level for the
>> ERSPs works?
>>
>> I am plotting an ERSP with actual values using 'baseline' NaN function
>> and setting the significance level using the function 'alpha',0.001. The
>> signals that remain after setting the significance level are significant
>> compared to what? I have the same question about ERSP plots with dB.
>>
>> Thanks,
>>
>> Nabi
>>
>>
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-- 
Max Cantor
Graduate Student
Cognitive Neuroscience of Language Lab
University of Colorado Boulder
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