Grammar Girl here. Today I'm going to talk about on accident versus by accident and how language changes.

Some of the most difficult questions I get are from non-native English speakers who want to know why we use a particular preposition in a specific phrase. Why do we say I'm in bed instead of I'm on bed? Do people suffer from a disease or suffer with a disease? Are we in a restaurant or at a restaurant? I’m a native English speaker, so my first thought is usually something like, “I don't know why; in bed just sounds right,” and sometimes either option seems correct.

Here's a question that a few people have asked:

Hi Grammar Girl. This is Tom Kennedy from Pleasanton, CA. What is the deal with the term on accident? I've always used by accident, but I've noticed a lot of pretty smart people . . . I've noticed them using on accident. So, am I wrong?

Sometimes when I get questions like this I can find an answer, and sometimes I can't. In this case, I hit pay dirt!  I was lucky enough to find an entire research paper on the topic, published by Leslie Barratt, a professor of Linguistics at Indiana State University (1).  

According to Barratt's study, use of the two different versions appears to be distributed by age. Whereas on accident is common in people under 35, almost no one over 40 says on accident. Most older people say by accident. It's really amazing: the study says that “on is more prevalent under age 10, both on and by are common between the ages of 10 and 35, and by is overwhelmingly preferred by those over 35.” I definitely prefer by accident.

An interesting conclusion from the paper is that although there are some hypotheses, nobody really knows why younger people all over the U.S. started saying on accident instead of by accident. For example, there's the idea that on accident is parallel to on purpose, but nobody has proven that children all across the country started speaking differently from their parents because they were seeking parallelism. Although I have no proof, I suspect that it must have something to do with nationwide media since it is such a widespread age-related phenomenon. Barney & Friends started airing about 30 years ago, so maybe it's Barney's fault! But really, all we can say is that it's just one of those language things that happens sometimes.

Finally, although there is at least one source stating that on accident is an error (2), and Shelly from Texas asked me to do what I can to ban on accident, Barratt found that there is no widespread stigma associated with saying on accident. In addition, it seems to me that as those kids who say on accident grow up (some of whom are even unaware that by accident is an option, let alone the preferred phrase of grown-ups) on accident will become the main, accepted phrase. By that time, there won't be enough of us who say by accident left to correct them!

That's all!
I have two copies of my audiobook to give away this week. Cortis and Sandy have won a copy of Grammar Girl's Quick and Dirty Tips to Clean Up Your Writing. And don't forget that you can get a free download of the audiobook at audible.com/grammar if you're a new Audible.com customer, or you can buy it at iTunes if you prefer.

If you have a question, my e-mail address is feedback@qdnow.com, and my voice-mail line is 206-338-GIRL.

Thanks for listening.


References

1. Barratt, L.  “What Speakers Don’t Notice: Language Changes Can Sneak In,”  Innovation and Continuity in Language and Communication of Different Language Cultures, ed. Rudolf Muhr (Peter Lang, 2006). Also in TRANS 16/2005: http://www.inst.at/trans/16Nr/01_4/barratt16.htm (accessed June 13, 2007).
2. Brians, P. Common Errors in English Usage. Wilsonville: William, James & Co. 2003. p.145.