[Eeglablist] Inquiry into Settings of Time/freq. parameters in Precompute Channel Measures

[u3564255 at connect.hku.hk]

Dear Cedric,

Thank you so much for your reply, Cedric. Also, thank you for the links.

You are right. It has something to do with the size of epochs. In the past, I visualised much longer epochs, so I forgot to pay attention to the lowest frequency of interest and the epoch length when visualising small epochs at hand. When I significantly increase the epoch length, the code works well. (Thanks Kathryn Nicole for her solution and reminder in her private reply.)

Cedric, could I ask a follow-up question? Will EEGLAB automatically remove segments contaminated by edge affects from wavelets in the visualisation?

Thank you so much!

Best regards,
Samuel
________________________________
From: Cedric Cannard <ccannard at protonmail.com>
Sent: 25 April 2023 02:52
To: u3564255 at connect.hku.hk <u3564255 at connect.hku.hk>
Cc: eeglablist at sccn.ucsd.edu <eeglablist at sccn.ucsd.edu>
Subject: Re: [Eeglablist] Inquiry into Settings of Time/freq. parameters in Precompute Channel Measures

Dear Samuel,

What bounds did you use when you epoched your data? Is it possible you segmented them from 70 to 700 ms? The epoch size should be bigger than your time limits to include these data points in the time-frequency estimation.

Not sure why you are getting this error, looks correct to me. Maybe double-check that you don't have typo. If the error persists, please submit an issue here: https://urldefense.com/v3/__https://github.com/sccn/eeglab/issues__;!!Mih3wA!BIY6n1JaX_JipvLwQmeChdawvPDTNB1HtlSDCOervtz7YCkuuGURAw0JPNzx6WVEtVCIH8Ouzw6mTmYbRG4rJ9gyG-FLfw$ 

In case you didn't see this yet, there is more detail on these parameters in the EEGLAB tutorial: https://urldefense.com/v3/__https://eeglab.org/tutorials/08_Plot_data/Time-Frequency_decomposition.html*timefrequency-decomposition__;Iw!!Mih3wA!BIY6n1JaX_JipvLwQmeChdawvPDTNB1HtlSDCOervtz7YCkuuGURAw0JPNzx6WVEtVCIH8Ouzw6mTmYbRG4rJ9iksIf-GQ$ 


Cedric



------- Original Message -------
On Sunday, April 23rd, 2023 at 11:56 AM, u3564255--- via eeglablist <eeglablist at sccn.ucsd.edu> wrote:


> Dear EEGLABList,
>
> I would like to ask for help to figure out how to set Time/freq. parameters in Precompute Channel Measures properly.
>
> Question 1
> I have been trying to visualise the time frequency data using Precompute Channel Measures. The current setting is 'cycles', [0.5 0.8], 'ntimesout', 2000, 'timelimits', [-200 1000], 'freqs', [1 60]. However, the two end points in the time axises are actually around 70 ms and around 700 ms. Could you please tell me why the two end points in the visualisation are not -200 ms and 1000 ms?
>
> Question 2
> Also, it seems that when I try to increase the number of circles of the wavelet (at 1 Hz) to 3 with all parameters having the same value (i.e., 'cycles', [3 0.8], 'ntimesout', 2000, 'timelimits', [-200 1000], 'freqs', [1 60]), EEGLAB generates an error message "error while calling function, check syntax". Could you please tell me why it happens?
>
> As I am new to time frequency analysis, I am confused by many things. Sorry if the answers are very obvious.
>
> Thank you so much in advance!
>
> Best regards,
> Samuel
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