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Data analysis
Posted: Tue Jul 17, 2018 5:10 am
by eof
Thanks for your APP and researches, I've read many articles on how brain works, about wave amplitudes / frequency, DSP and so on.
But it is difficult for me to understand all of this and I want to ask more experienced people who are on this forum,
What kind of brain activity can be seen on these pictures?
1.
http://pichost.org/image/2pTKA
2.
http://pichost.org/image/2p2YF
3.
http://pichost.org/image/2ptmi
4.
http://pichost.org/image/2pssa
5.
http://pichost.org/image/2pOEs
Thank you for all replies
Re: Data analysis
Posted: Tue Jul 17, 2018 11:17 am
by James
I don't think nearly as many people read my little forum as the Interaxon one, but here's my take
#1+5 - Online Charts - These both show the same data, with and without smoothing to the minute. This is a pretty short time period, so it's hard to draw any real conclusions. For relaxation most believe that what you want to look at is how your average Alpha change from session to session. So here, your Alpha level is very similar throughout, averaging at around 0.3, which you can see from the gauge at the bottom. So whatever state you were in if that was relaxed or neutral, you maintained it for the duration of the session fairly evenly. If you compare this to future sessions you should see it raise slightly as you become more relaxed. You may also find that rather than Alpha going up, others bands will go down, thus "relative" Alpha is higher. This is also good from a meditation standpoint and you can see it happening at the 11:41/11:42 mark.
The left vs right gauge shows an almost perfect balance with everything ever so slightly biased to the right. There are some people who call this "coherence" and believe getting this exactly centred is the key to meditation. If their theory is right, you're doing great
#2 - Spectrogram - Everything looks very even, so there's no noticeable change in state, you were probably relaxed or at least not moving for the most part. At the bottom left corner you can see a large increase in lower band powers as the red area. This was likely when you broke concentration to look at your device and take the screenshot
#3 - Discrete - Looks like a fairly standard nice even distribution, consistent with the other views. No eye movement. Head still. No electrical interference from outside sources.
#4 - RAW EEG - I can see that you have a good fit on your headband. There are nice small bumps in the raw data. I can also tell you didn't blink for the data that's on the screen as that would show a large spike.
Hope that helps!
Re: Data analysis
Posted: Tue Jul 17, 2018 1:37 pm
by eof
Thank you VERY VERY VERY much for such detailed reply. I should be expecting a reply: "everything is good" :D
All graphs above I was trying to be in meditation state.
Recently after hard brain work (in final with a headache) I lay down to measure wave activity and got the following picture
http://pichost.org/images/2018/07/17/1.png
If I understand correctly, if higher the axis in the graph, so the greater number of such waves in brain activity,
if yes, why usually i have on all 5 sensors the top power is Delta, then Theta, then Alpha? (not even in meditation state)
On graph above avarage top is Delta too, why not Beta or Alpha, which indicates normal brain state? is it
normal?
If you have paypal, i want to send a tip:) for humanity, thank you! :-))))
Re: Data analysis
Posted: Tue Jul 17, 2018 1:49 pm
by James
You need to check the numbers on the axis as the graph by default is auto-scaling; but yes, higher numbers = more brain activity.
Which wave is on top doesn't matter as each wave is comprised of different frequencies and should be considered independently.
Delta is the most susceptible to eye movement interference, so if you blink a lot, or move your eyes Delta will go up due to the interference from the electric signals to your facial muscles. If you've got a headache you might be involuntarily furrowing your brow which will cause this. .. which could be considered into your calculation as a stress indicator, or you could choose to exclude it as it's not really brain wave data.
Re: Data analysis
Posted: Tue Jul 17, 2018 1:54 pm
by eof
James, thank you,
you helped me a lot!
Re: Data analysis
Posted: Tue Dec 04, 2018 10:58 am
by Strick
i remain confused about the appopiate way to describe changes i am seeing in the graph and the dB numbers in the left hand corner. i have read that the number on a dB scale are sopposed to be logarithmic. however the graph itself looks liniar. For example, when Delta dB number moves from 100 to 50 the graph moves about half way down the screen
What would be the appropriate way to describe such a change. Would it be “50% reduction” or would “it reduced by some power”
Similar question, would it be appropriate to characterize is the brain frequency that the graph as the “dominant “ frequency and if the dB numbers on the upper left for one is 75 and the other is 25 is it appropriate to say that the lower number to be 1/3 of the upper .
Re: Data analysis
Posted: Tue Dec 04, 2018 9:03 pm
by James
The values are derived using logarithmic functions, but the values move in a linear fashion. The dB scale isn't 0:100, the numbers can go above or below this, so 50% isn't correct, "some power" would be the most appropriate language.
If one number is higher than the other, then it would be more dominant in the brain, but remember brain waves represent a group of frequencies, so don't say "dominant frequency" say "dominant frequency range". If you want the actual individual dominant frequency for a given point in time, you can look at the discrete frequency graph.