[Eeglablist] ersp output from timef

[Makoto Miyakoshi]

Dear Katherine,

> why is ersp a 256x200 matrix?

They represents 256 freqs x 200 latencies.

In the same workplace, you should have 'times' and 'freqs'. I guess 256
corresponds freqs, so your 'freqs' must be 1x256. When you open it, you'll
notice something like 3, 3.5, 4.1,... which means your first raw is for
your 3 Hz decomposition, the second raw is 3.5 Hz, the third raw 4.1 Hz,
etc. If you use 'nfreqs' to be 50, then you'll get 50 freqs instead of 256
(actually 256 is too many).

I guess your 200 derives from the default times out value of 200. When you
open 'times' you'll see some numbers; they represents latency (ms).

Makoto

2013/7/4 Katherine Naish <K.R.Naish at pgr.reading.ac.uk>

>  Hi all,
>
>
>
> Sorry for the basic question, but I am struggling to understand exactly
> what the ersp values produced by timef represent. I thought that I
> understood the analysis at a reasonable level, but now that I have run the
> analysis I'm not sure which values I should be extracting in order to
> average across participants.
>
>
>
> I have data from 128 channels, (re)sampled at 500hz. One specific question
> I have is what the x and y coordinates of the 'ersp' variable represent? I
> have read the help file and various other documents, but can't work out
> what 'nfreqs' and 'timesout' actually mean- why is ersp a 256x200 matrix?
>
>
>
> Any help greatly appreciated,
>
> Katherine
>
>
>   -------------------------------
> Katherine Naish
> School of Psychology
> University of Reading & Goldsmiths University of London
> +44(0)118 378 6946
> http://www.neurobiography.info/handlab.php?page=people#Katherine-Naish
>       ------------------------------
> *From:* eeglablist-bounces at sccn.ucsd.edu [eeglablist-bounces at sccn.ucsd.edu]
> on behalf of Nikola Vukovic [vukovicnikola at gmail.com]
> *Sent:* 28 May 2013 04:48
> *To:* EEGLAB List
> *Subject:* [Eeglablist] Extracting average ERSP values for statistical
> analysis
>
>      Dear EEGlab Community,
>
>  I wonder if anyone can help me with the following issue:
>  >From my Study design, I would like to extract (for each participant and
> condition) the average power in a specific frequency band and a specific
> time window. I would like to export these values into SPSS for statistical
> analysis.
>  I should also note that I am working with IC Clusters, so the above ERSP
> measures should be cluster specific.
>  Does anyone know a script which would help me achieve this?
>
>  Yours gratefully,
>  Nikola
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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