Here's the comment thread for my Bonobo Conspiracy archive posting.
In 2005 through 2008 I wrote and posted a Web comic called Bonobo Conspiracy. I posted a new strip with a new joke every single day for just over 1000 days, chronicling the lives, thwarted romances, and mad science of Matt, Sun-Moon, Dr. Klaun, Algea, and a host of special guests. Although most strips were designed to stand on their own, I also gradually developed each character over the course of the run, and I ran a few multi-strip specials and storylines.
I saw a Web BBS posting recently in which the poster, who was a foreigner learning English as a second language, asked "Which is correct - 'based off' or 'based off of'?" The person asking the question can probably be forgiven because they don't know any better, and at least were smart enough to ask, but if you know me you'll probably be able to guess that the general agreement among the answers, that "based off of" is incorrect and you should say "based off" instead, caused me to consider the merits of a tri-provincial killing spree.
I will not apologize for being a prescriptivist. There are some usages that would be wrong even if all the other native speakers of English used them; and "based off" (with or without an "of") is such a usage. I'm willing to accept "different than" as an issue of formalism, and acceptable in speech or informal writing even though I do not use it myself; I'm willing to (very grudgingly) grant that persons from the United States of America may be allowed to say "anyways" as a regional dialect thing, even though it makes them sound illiterate; but "based off" is just completely unacceptable.
Nonetheless, from a scientific perspective and from the point of view of "know the enemy," it may be interesting to look seriously at the questions of who does say "based off," and when they started.
Expanded from a Twitter tweet, since there are important points here that won't fit in 140 characters.
Our text for the day is Achewood, 2010:5:9-24 (starts here). Andy Larson dares "Darin'" Darren Wilson to ride in an unsafe vehicle without a seatbelt and then leave a bowel movement on the math teacher's lawn. Darin' Darren does so, at great risk to his life both from Andy's reckless driving and from illegal chernchilla breeders Mayner and Lurquilla. He retaliates by daring Andy to have dinner at Denny's naked. And in the last panel, Andy smiles.
Andy doesn't give a crap, pun intended, about Darin' Darren's doings on the math teacher's lawn, and he knows dehrn well that neither Mayner nor Lurquilla is in fact a math teacher anyway. (The range of Mayner's scholarship suggests rather a career in law.) Andy only put Darren through the horrible experiences in the back of the van and on the lawn so that Darren would make a counter-dare of his own. But if Andy wanted Darren to make a dare, why not just say so? And, for that matter, why doesn't Andy just go to Denny's naked under his own power if that's what he wants to do, instead of hoping to be dared into it? Andy could show up naked at Denny's any time he wants to - they are, famously, open 24 hours a day.