Re: Proof 2=1

Posted by Bruce Weaver on Dec 12, 2018; 9:04pm
URL: http://spssx-discussion.165.s1.nabble.com/Proof-2-1-tp5737153p5737164.html

Q1. How many possible values of Pearson r are there?  
A1. Two, one negative and one positive.

Q2. How do you choose which one to use if no additional info is provided?
A2. I have no idea what you're fishing for here, Mike, but here's one
possible approach:  Report the positive square root of r^2 and describe it
as the correlation between y and y-hat (which is always non-negative, even
if the correlation between x and y is negative).  

Okay, now maybe you can tell us what you're really looking for!  ;-)  



Mike wrote

> This is a somewhat old chestnut, so let me provide a novel conundrum.
>
> Consider:
> A person reports the result of a correlational analysis and only reports
> the valuw od r^2.  There are no scaterplots, no raw data, nthing except
> the "effect size" measure r^2.
>
> Question:  What is the value of the Pearson r?
>
> A better question is "how values of Pearson r are there and how do you
> choose which one to use if no additional info is provided?" ;-)
>
> -Mike Palij
> New York University

> mp26@

>
> P.S.  I'm getting well again.
>
>
> On Tue, Dec 11, 2018 at 11:54 AM Martin Holt <

> 000002126fbb7baa-dmarc-request@.uga

>> wrote:
>
>>  *Xmas draws nearer!*
>>
>>
>> *For  young statisticians...some festive fun*
>> *Proof that  2 = 1*
>> a = b
>> a2 = a.b
>> a2 + a2 = a.b + a2
>> 2a2 = a.b + a2
>> 2a2 – 2ab = a.b + a2 – 2ab
>> 2a2 – 2ab = a2 – a.b
>> 2(a2 – a.b) = a2 – a.b
>> Dividing through by (a2 – a.b) gives 2=1
>> Q.E.D.
>>
>> Martin P. Holt
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