Re: delta theta coherences

[Guest guest]

Not sure exactly what you mena by upper limit. Coherence can't go above 1.0, so

that's an upper limit. The target I would have would generally be around 40-70

for slow frequencies.

Pete

>

> From: " Rosemary Herron " <reherron@...>

> Date: 2006/02/06 Mon AM 11:34:52 EST

> < >

> Subject: delta theta coherences

>

> MessagePete,

>

> Is there an upper limit for delta and theta coherences, Eyes Closed and also

Eyes Open?

>

> Thanks,

>

> Rosemary

>

[Guest guest]

Can anyone explain the difference between coherence and the co-efficient of variance as produced by Biograph which often is 0.40 to 0.70 roughly and never greater than 1.0?

Mark

delta theta coherences> > MessagePete,> > Is there an upper limit for delta and theta coherences, Eyes Closed and also Eyes Open? > > Thanks,> > Rosemary>

[Guest guest]

Coherence is a measure of the degree to which two separate signals are alike.

The co-efficient of variance is a measure of how stable or unstable an

individual signal is.

Variance is the average of the squares of all the differences between individual

readings and the average reading for, say, theta at a certain site. If all the

readings are very close to the mean, then the variance will be very small. If

they are spread all over the place, you can still calculate an average, but the

variance will be quite high. Take the square root of the variance, and you have

the standard deviation. Divide the standard deviation by the average or mean,

and you have the co-efficient of variance. The larger the number, the more

spread out are the individual values.

For example (I'm going to fudge the calculation slightly to make the math

simpler):

There are six readings of theta: 28, 12, 16, 6, 32, and 14. The average of

those readings would be 18.

If we compared each individual reading against the average, by subtracting the

average from the reading, we'd have 10 (28-18), -6 (12-18), -2, -12, 14 and -4.

We would square each of these numbers (to get rid of the minus signs) and take

the average of those squared numbers (486/6=) 81. That would be the variance.

The square root of 81, or 9, would be the standard deviation. 9 divided by the

average reading of 18 would be 0.5. That's the co-efficient of variance.

If we took another set of readings, 18, 18, 18, 18, 18 and 18, the standard

deviation would be 0, since each measurement was equal to the average, and the

co-efficient of variance would be 0 also.

This has confused the hell out of me, so I assume I've done the same for the

rest of you, and I'll go to bed.

Pete

>

> From: " Mark Baddeley " <baddeley@...>

> Date: 2006/02/06 Mon PM 06:21:49 EST

> < >

> Subject: Re: delta theta coherences

>

> Can anyone explain the difference between coherence and the co-efficient of

variance as produced by Biograph which often is 0.40 to 0.70 roughly and never

greater than 1.0?

> Mark

[Guest guest]

Thanks, Pete. If I were to put another mathemeatical tag onto coherence then it would be correlation co-efficient. Is that correct?

Mark

Re: delta theta coherences> > Can anyone explain the difference between coherence and the co-efficient of variance as produced by Biograph which often is 0.40 to 0.70 roughly and never greater than 1.0?> Mark

[Guest guest]

Pete ! Bravos !

I understand substance Your statements, but numbers me do not fit:

Pete :(486/6=)81....;The square root of 81, or 9, would be the standard deviation.

Jan : exactly : (496/6=) 82.67 The square root of 82.67=9.09 ....Counted according to idea Pete.

EXCEL : standard deviation(28,12,16,6,32,14) = 9.96

Pete - where is truth ?....and can I make a mistake?

Jan

Re: delta theta coherences> > Can anyone explain the difference between coherence and the co-efficient of variance as produced by Biograph which often is 0.40 to 0.70 roughly and never greater than 1.0?> Mark

[Guest guest]

Pretty close. We're outside my area of expertise here, but that's as I

understand it.

Pete

>

> From: " Mark Baddeley " <baddeley@...>

> Date: 2006/02/07 Tue AM 12:24:31 EST

> < >

> Subject: Re: Re: delta theta coherences

>

> Thanks, Pete. If I were to put another mathemeatical tag onto coherence then

it would be correlation co-efficient. Is that correct?

> Mark

> Re: delta theta coherences

> >

> > Can anyone explain the difference between coherence and the co-efficient

of variance as produced by Biograph which often is 0.40 to 0.70 roughly and

never greater than 1.0?

> > Mark

>

>

>

>

[Guest guest]

Jan,

I thought you might catch me there. That is why I said at the beginning of the

example that I " fudged " the calculation. I miscalculated a little bit to get

the 81, so the square root would be 9 instead of 9.09. I thought it would be

easier for people to follow who are NOT comfortable with math.

Good to have an engineer who is so quick with his math to keep me honest.

Thanks,

Pete

>

> From: " STUDIO EEG-BIOFEEDBACK. POLAND " <soliserw@...>

> Date: 2006/02/07 Tue AM 09:43:54 EST

> < >

> Subject: Re: Re: delta theta coherences

>

> Pete ! Bravos !

> I understand substance Your statements, but numbers me do not fit:

>

> Pete :(486/6=)81....;The square root of 81, or 9, would be the standard

deviation.

> Jan : exactly : (496/6=) 82.67 The square root of 82.67=9.09 ....Counted

according to idea Pete.

> EXCEL : standard deviation(28,12,16,6,32,14) = 9.96

> Pete - where is truth ?....and can I make a mistake?

> Jan

> Re: delta theta coherences

> >

> > Can anyone explain the difference between coherence and the co-efficient

of variance as produced by Biograph which often is 0.40 to 0.70 roughly and

never greater than 1.0?

> > Mark

>

>

>

>

[Guest guest]

Thanks Pete. That's what I meant...but I only remembered it was mentioned in reference to alpha and didn't know if it applied to delta and theta the same way.

Rosemary

delta theta coherences> > MessagePete,> > Is there an upper limit for delta and theta coherences, Eyes Closed and also Eyes Open? > > Thanks,> > Rosemary>

[Guest guest]

Mark,

I believe the coherence number on the TLC is correlation co-efficient without the decimal poiint....soooo 1 =100 .5 = 50

Rosemary

delta theta coherences> > MessagePete,> > Is there an upper limit for delta and theta coherences, Eyes Closed and also Eyes Open? > > Thanks,> > Rosemary>

[Guest guest]

Pete !

Your explanations definition variance and standard deviation( although small error in adding up)

is mathematics correct. I did a couple of calculations( other numbers) "by hand" and automatically in EXCEL.

Results should be identical, but are not. Is difference 5-10 %.

On this stage I do not understand this occurrences. Both results( yes I think) should be identical.

For explanations I will ask doctors mathematics ).

Jan

Re: delta theta coherences> > > > Can anyone explain the difference between coherence and the co-efficient of variance as produced by Biograph which often is 0.40 to 0.70 roughly and never greater than 1.0?> > Mark> > > >

[Guest guest]

Thanks Rosemary. That was the understanding I was coming to based on some months of digging into states and searching the net but I had not found anyone saying exactly that.

Mark

delta theta coherences> > MessagePete,> > Is there an upper limit for delta and theta coherences, Eyes Closed and also Eyes Open? > > Thanks,> > Rosemary>

[Guest guest]

Pete:

Un huh. I got all that. Now what does variance have to say about training

my heads?

Re: delta theta coherences

>

> Can anyone explain the difference between coherence and the co-efficient

of variance as produced by Biograph which often is 0.40 to 0.70 roughly and

never greater than 1.0?

> Mark

[Guest guest]

Generally the more stable the brain's activation patterns, the more regulated it

is and the better it will perform. So, if a client has high levels of

variability, or high levels in particular frequencies, you have the option of

choosing to train it down. Training down amplitude often reduces variability as

well.

Pete

>

> From: " " <jccamp@...>

> Date: 2006/02/10 Fri AM 10:01:29 EST

> < >

> Subject: RE: Re: delta theta coherences

>

>