# one tiny question for clever maths peopleWatch

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#1
is the symbol for standard deviation lower case sigma, and is the symbol for spearman's correlation coefficient rho?

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15 years ago
#2
(Original post by me!)
is the symbol for standard deviation lower case sigma, and is the symbol for spearman's correlation coefficient rho?

yep sort off.

rho represents both product moment and spearmans rank as the estimated correlation of the population at a certain significance level.

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#3
(Original post by Meeps)
yep sort off.

rho represents both product moment and spearmans rank as the estimated correlation of the population at a certain significance level.

thanks

I might just use the r subsript thing >>>s for spearmans
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15 years ago
#4
(Original post by me!)
is the symbol for standard deviation lower case sigma, and is the symbol for spearman's correlation coefficient rho?

Sigma on its own regardless of whether it is lower or upper case is the standard deviation. Variance is S.d squared.
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#5
(Original post by Bhaal85)
Sigma on its own regardless of whether it is lower or upper case is the standard deviation. Variance is S.d squared.
I don't suppose you would know how to work out PMC? I've got this formula for spearman's rank, and I've worked that out...
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15 years ago
#6
(Original post by me!)
I don't suppose you would know how to work out PMC? I've got this formula for spearman's rank, and I've worked that out...
Product moment correlation coeffiecent?
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#7
(Original post by Bhaal85)
Product moment correlation coeffiecent?
yep... is spearmans rank and spearmans rho the same thing?
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15 years ago
#8
(Original post by me!)
yep... is spearmans rank and spearmans rho the same thing?
I have done Spearmans ranks correlation coefficient but not rho, what is that?

Would you like me to explain how to do PMCC?
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15 years ago
#9
(Original post by Bhaal85)
I have done Spearmans ranks correlation coefficient but not rho, what is that?

Would you like me to explain how to do PMCC?
Jsut curious, but why on earth are they allowing you to do PMCC, as it is A-level stats?
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#10
(Original post by Bhaal85)
Jsut curious, but why on earth are they allowing you to do PMCC, as it is A-level stats?
it's GCSE... yeasssss I would be very greatfull if you could explain it

I think spearmans rank and spearmans rho is the same thing but i'm not sure...

EDIT: I meant I'm doing GCSE stats, not that PMCC was GCSE
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15 years ago
#11
(Original post by me!)
it's GCSE... yeasssss I would be very greatfull if you could explain it

I think spearmans rank and spearmans rho is the same thing but i'm not sure...
Well I only got 90/100 in Statistics 1 at A-level. I'll try my best.

PMCC = Sxy / (Sxx * Syy) where:

Sxy = SigmaXY - 1/N(SigmaX*SigmaY)
Sxx = SigmaX^2 - N(X mean squared)
Syy = SigmaY^2 - N(Y mean Squared)
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15 years ago
#12
(Original post by Bhaal85)
Well I only got 90/100 in Statistics 1 at A-level. I'll try my best.

PMCC = Sxy / (Sxx * Syy) where:

Sxy = SigmaXY - 1/N(SigmaX*SigmaY)
Sxx = SigmaX^2 - N(X mean squared)
Syy = SigmaY^2 - N(Y mean Squared)
You will basically set out five collums, with the headings 'X', 'Y', 'X^2', 'Y^2', AND 'X*Y'. You would then enter the appropriate values. 'N' would represent the number of pairs of data.

E.g

(2,3), (4,5), (2,0)

In the above case 'N' would be three.

After entering the data in the appropriate collumns. You would then calculate the total for each column, hence the Sigma. So the the total of the 'X' column would be called SigmaX, the total of the column 'Y' would be SigmaY, the total of the column 'X*Y' would be called SigmaXY, etc.
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15 years ago
#13
http://www.mathsnet.net

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#14
Thanks Bhaal, it looked kind of complicated but I think I actually understand it
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15 years ago
#15
(Original post by me!)
Thanks Bhaal, it looked kind of complicated but I think I actually understand it
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#16
I got another question if anyone would like to help me... Has variance got something to do with the least squares regression line thing?
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