On Thu, 09 Oct 2014 18:23:19 -0700, Carol DeVolder wrote:
Perhaps others are familiar with this site, but I wasn't. It's a fun
collection of spurious correlations. Good for examples in class.
http://tylervigen.com/
For people interested in such things, I suggest one take a look
at some of Brian Haig's writing on spurious correlations which
provides a more "nuanced" perspective on them (one can classify
spurious correlation between those that are truly spurious versus
those that are not). Here's the reference for one of his articles:
Haig, B. D. (2003). What is a spurious correlation?. Understanding
Statistics: Statistical Issues in Psychology, Education, and the
Social Sciences, 2(2), 125-132.
http://www.tandfonline.com/doi/abs/10.1207/S15328031US0202_03#preview:
or
http://psycnet.apa.org/psycinfo/2004-12710-003
A key point is whether a correlation represents a direct "effect" or
relationship (which is typically assumed in a correlational analysis) or
an indirect "effect" or relationship exists between two or more
variables.
If we have three variables X, Y, and Z, and
(1) there is no direct relationship between X and Z
but
(2) there is an indirect relationship X -> Z -> Y
This raises thorny questions of mediation and moderation which I will
leave to Karl Wuensch to elaborate (or to provide access to his notes
on the these topics ;-).
Haig would probably call the correlations provided on the Tyler Vigen
website "nonsense correlations" but, for fans of the belief of
"everything
is connected to everything else", one might refer to the "butterfly
effect".
The butterfly effect refers to two conceptually unrelated events
(apparently
nonsensical) but which are connected by a complex nonlinear
relationship.
Simple correlational analysis that (a) do not have the necessary
intermediate
variables, and/or (b) do not have the necessary nonlinear terms, will
not
accurately represent the relationship or, more correctly, the process
that
connects two variables.
Just something to think about. ;-)
-Mike Palij
New York University
[email protected]
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