Advanced quantitative analysis often controls for variables that aren’t of central interest. But what does it mean to “control for” a variable? XKCD offers a fun example.
So, do subscribers to Martha Stewart Living live alongside furries? Probably not. In any case, these maps don’t offer any evidence in favor of this conclusion. This is because of a variable that hasn’t been controlled for: population density.
To control for population, one would have to divide the number of subscribers/furries by the total population. This would give us the percentage of the population that is described by both proclivities, instead of the sheer number of devotees. Then the maps would actually show variance in the proportion of the population instead of variance in the population itself.
In other words, we would have controlled for population in order to get a closer look at what we’re really interested in: furries, of course.
Lisa Wade, PhD is an Associate Professor at Tulane University. She is the author of American Hookup, a book about college sexual culture; a textbook about gender; and a forthcoming introductory text: Terrible Magnificent Sociology. You can follow her on Twitter and Instagram.
Comments 13
msilfan — January 12, 2013
Reminds me of the hysterically funny Twitter hashtag #overlyhonestmethods - I'd love to see one of you do a post on that!
L — January 12, 2013
That's why using choropleths to represent magnitude is wrong.
Yrro Simyarin — January 13, 2013
Do any colleges have their stats department farm out grad assistants to help with this stuff? I've seen some pretty horrible abuse of statistics in pretty much all fields of research.
EB — January 15, 2013
This analysis misses the actual point of the xkcd cartoon that is a joke for GIS analysts and census data users - the three maps are basically slight variations of census maps of the population density the US.
Because of this, yes, more furries, the website users, and martha steward living subscribers are probably located in areas of high population density.
This is not about control variables at all, but rather, poking fun of the trend where reviewers/customers want you to GIS map where the users/consumers/respondents who do X are located. A fair number of times you may find that more <> are located in heavily populated areas.
As a result, the point is, when GIS mapping, be aware of what you are doing.
What Does it Mean to “Control For” Something? » Sociological Images | digitalnews2000 — January 15, 2013
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plum — December 27, 2016
no wonder america is ranked where it is in education just look at the arrogant way critical units of knowledge are explained to the general public. this scholar's poor explanation is no differ from what the average scholar spurts out in colleges and universities. there is nothing 'fun' here.