One thing I have found helpful in teaching the concept of spurious correlations is to have students populate a number of columns in a spreadsheet with random numbers and then calculate correlations between all the columns of random numbers. Since they are random, the correlation in the population from which all of these samples are drawn is 0. For every 100 correlations calculated in this circumstance, using a .05 alpha level, students will find about five spurious correlations that are statistically significant but are clearly spurious (mind blown) :)
Rick Dr. Rick Froman Professor of Psychology Box 3519 John Brown University 2000 W. University Siloam Springs, AR 72761 rfro...@jbu.edu<mailto:rfro...@jbu.edu> (479) 524-7295 http://bit.ly/DrFroman "The LORD detests both Type I and Type II errors." Proverbs 17:15<http://www.biblegateway.com/passage/?search=proverbs%2017:15&version=NIV> -----Original Message----- From: Mike Palij [mailto:m...@nyu.edu] Sent: Friday, October 10, 2014 8:17 AM To: Teaching in the Psychological Sciences (TIPS) Cc: Michael Palij Subject: re: [tips] Spurious Correlations 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 m...@nyu.edu<mailto:m...@nyu.edu> --- You are currently subscribed to tips as: rfro...@jbu.edu<mailto:rfro...@jbu.edu>. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13039.37a56d458b5e856d05bcfb3322db5f8a&n=T&l=tips&o=39061 or send a blank email to leave-39061-13039.37a56d458b5e856d05bcfb3322db5...@fsulist.frostburg.edu<mailto:leave-39061-13039.37a56d458b5e856d05bcfb3322db5...@fsulist.frostburg.edu> --- You are currently subscribed to tips as: arch...@mail-archive.com. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=39063 or send a blank email to leave-39063-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
