[Eeglablist] newtimef automated stepsize?

[Makoto Miyakoshi]

Dear Joshua,

Sorry for belated response.

> For example, if you define freqs as [3 50], and a 250ms window size is
chosen by the algorithm, to estimate power at 3 hz, you would require a 333
ms time window to capture a full cycle. How is it that the TF image can
show fluctuations in 3Hz power within a 200ms segment of time?

If you do this, I believe the function performs wavelet(-like) transform
starting from 1/(0.25s/3cycles) = 12Hz and never goes down to 3Hz even if
specified. You should be able to confirm it in the result.

Makoto



On Fri, Mar 31, 2017 at 1:54 AM, Baker, Joshua <joshua.baker at ntu.ac.uk>
wrote:

> Dear list,
>
>
>
> When using the newtimef function in eeglab (cycles=0, using STFFTs), and
> you do not specify winsize or stepsize, how does the algorithm chose them?
> Also, how is it that a TF image when using STFFTs shows variations in low
> frequencies at a time scale that is too small to fully capture a full cycle
> of the frequency? For example, if you define freqs as [3 50], and a 250ms
> window size is chosen by the algorithm, to estimate power at 3 hz, you
> would require a 333 ms time window to capture a full cycle. How is it that
> the TF image can show fluctuations in 3Hz power within a 200ms segment of
> time?
>
>
>
> Thanks for your help
>
>
>
>
>
> Joshua Baker
>
> Psychology Technician (Behavioural Neuroscience)
>
> Psychology
>
> Nottingham Trent University
>
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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