[Blindmath] statistical formulas

[Ryan Thomas]

Yes, it's the product of the deviation from the mean in each variable
summed.  It looks like

sum from i = 1 to n of (xi-xbar)*(yi-ybar) where xbar and ybar are the
means.  I'm not sure what you mean by raw scores versus deviations.
You can get around not computing the covariance by using some of the
other identities which may avoid the deviations, but it's not very
difficult if you use some computer application anyway.

On 10/23/12, Kathy Roskos <kroskos at cox.net> wrote:
> Thanks for the help.  I am really dense where math is concerned.  What
> exactly do you mean by the covariance?  Do I use deviation scores and figure
>
> the variances for both  X and Y and multiply them together?
>
> I have read  that you can use raw scores or deviation scores to figure
> correlations.  Which method is easiest?
>
> Kathy
> Please excuse my ignorance.  I have  ----- Original Message -----
> From: "Ryan Thomas" <rlt56 at nau.edu>
> To: "Blind Math list for those interested in mathematics"
> <blindmath at nfbnet.org>
> Sent: Tuesday, October 23, 2012 8:01 AM
> Subject: Re: [Blindmath] statistical formulas
>
>
>> For random variables X and Y, the correlation coefficient r is the
>> covariance between x and y divided by the product of the variances of
>> X and Y.  Depending on what statistics you're in there are other
>> identities dealing with sum of squared regression and other terms.  I
>> hope that's helpful though.
>>
>> On 10/23/12, Kathy Roskos <kroskos at cox.net> wrote:
>>> I am new to this list.  I am taking a statistics class online and am
>>> having
>>> trouble getting jaws to read the formulas.  Does anyone out there know
>>> about
>>> calculating r values for correlational data?
>>>
>>> any advice would be appreciated.
>>>
>>> Kathy
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