[Eeglablist] (Too) long of an explanation and questions at the end
sharonjalene at gmail.com
Sun Feb 2 15:20:54 PST 2014
I am proposing a project in Motor Control for my thesis. My school does
not have an EEG presence. I earned $$ to buy an EMOTIV research edition,
extra electrodes, MATLAB and other software, and a dedicated laptop. I
took a MATLAB course, attended the recent EEGLab workshop, and continue to
work through the tutorial and material from the workshop. I truly want to
learn this technology and do more research in Motor Control. What I have
to start with is the EMOTIV and EEGLab. There are 2 Biomechanists on my
committee who are looking at this with interest for future projects - and
I will be doing 60-second data collection periods in a Control and 2
different FOCUS Conditions during an unstable balance task. Additionally,
I will be looking at the RMSE of postural sway between conditions. I also
intend to play recorded focus instruction at 15 sec intervals to control
for mind wandering and to have a place to sync/mark the data for future ERP
and ERSP analyses. This far, I have been processing it as continuous data.
It has been my intention compare 8-12Hz and 12-25Hz readings from the left
and right electrode arrays, the L & R frontal array, and the L & R - TPO
I have waited to post until I could ask reasonable questions. First, I do
understand that looking at components instead of electrodes is much
preferred, but to start, I have opted to look at channels to keep it simple.
I am in the unusual position of using tech/software that no one here is
familiar with, and I am learning it as fast as I can... Whatever I do, I
have to be able to explain it clearly- rather teach it. I am running into
roadblocks, but it forces me to learn.
*1. **Should I epoch the data before statistical analyses even though I
am looking at the differences between the Grand Average - within subjects?*
*2. *I am HP filtering at 1Hz and using Cleanline, automatic artifact
rejection, visual artifact rejection. I have played with ICA component
rejection, but am not sure I have enough good data to do so. (I recorded
pilot data on one subject - I have 3 minutes of data for each condition and
14 electrodes). *Is there an optimal filtering method since I am using
*a. *One of my committee said I should NOT filter the data or remove
artifacts since I am just looking for the Grand Average of certain freq
bands. Although I see his logic, I believe I should still remove spurious
data so that the mean is not skewed by muscle and other artifacts... right?
*3. *I was able to create a STUDY. I saved separate data sets with the
electrodes of interest. I was able to run power spectrum channel stats as a
3 (conditions) X 2(Left and Right) ANOVA. I saw the t-tests between
conditions and the interaction.
*a. *Is the power spectrum giving me the average of the specified freq
*b. *If I epoch the data, can I use Bootstrapping instead of parametric
*c. *How can I get the actual values, including the p values, of the
stats? I see the option to show a table with statistics containing the
median, mean, mode, etc., but it rarely populates and is inconsistent. IS
that statcond - on?
*d. *If I show results from a bootsrap, what statistical test was used
to obtain the results?
*e. *Would I be better off using a ratio of Grand Average subtraction
of the control from the FOCUS conditions. or pwelch in MATLAB -then
dropping the data into SPSS for some non parametric analysis (WIlcoxon rank
I am being encouraged to use as simple of methodology as possible for the
*If one dream should fall and break into a thousand pieces, never be afraid
to pick one of those pieces *
*and begin again.*
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