A Little Multiplication Could Have Gone a Long Way:

The Oregon State University newspaper (The Daily Barometer) had this to say last week:

According to a press release issued by the Women’s Center, 2,000 rapes occur every five minutes.

Huh -- 2,000 rapes every five minutes. That would mean 2000 x (60/5) x 24 x 365 = 200 million rapes a year (presumably in the U.S.). Many people underestimate the frequency of rape. Still, one would hope that it doesn't happen 200 million times a year; at least a little bit of multiplication should have alerted the writer and the editor that something was wrong.

Something was indeed wrong; when I e-mailed the Barometer to ask what the source was, they pointed me to the press release they were citing. It reads:

About 2,000 rapes are committed daily at the rate of about one every 5 minutes.

Not 2,000 rapes every five minutes, it turns out, but 2,000 rapes daily, or one every 5 minutes. Off by a factor of 300 (5 x 60) from how the newspaper rendered it.

But wait! A "rate of about one every 5 minutes" would be about 300 daily ((60/5) x 24), not about 2000 daily. The Women's Center press release was also mistaken (on at least one of the statistics, and maybe both); and again a little multiplication would have helped catch this.

For those who are interested about what the real number actually is, the answer of course is that we don't know for sure. The National Crime Victimization Survey, a survey of noninstitutionalized Americans age 12 or over, estimates that there were 72,000 completed rapes in the U.S. in 2003, plus 45,000 attempted rapes, and 82,000 sexual assaults (completed or attempted attacks short of vaginal, anal, or oral penetration); the 72,000 number would of course translate into roughly 200 rapes daily, not 2000. On the other hand, other studies have reported considerably higher levels, including the 700,000 number that corresponds to 2000 daily (though this was from the early 1990s, and the rape rate has apparently fallen considerably since then). To my knowledge, there continues to be a hot debate about the number (though not about whether 60/5 x 24 = 2000).

I e-mailed the Daily Barometer and the Women's Center to ask what's up, and to suggest that a correction be published (or, as to the web site, simply made); no response from them yet, I'm afraid.

(Note that the NCVS site was down when I checked the link; I fortunately have a printout from which I read the data, but I wanted to alert people that they might have trouble accessing the data themselves.)

Related Posts (on one page):

  1. Multiplication:
  2. More Multiplication:
  3. Following Up on "A Little Multiplication":
  4. A Little Multiplication Could Have Gone a Long Way:
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Following Up on "A Little Multiplication":

Last week I blogged, under the title "A Little Multiplication Could Have Gone a Long Way," about this claim in the Oregon State University newspaper (The Daily Barometer):

According to a press release issued by the Women’s Center, 2,000 rapes occur every five minutes.

I pointed out two things:

  1. The assertion should have led the author and the editor to be skeptical, since it would mean 2000 x (60/5) x 24 x 365 = 200 million rapes a year (presumably in the U.S.), a truly vast number. And in fact, the press release on which they were relying didn't say that; rather, it said, "About 2,000 rapes are committed daily at the rate of about one every 5 minutes."

  2. Moreover, the press release itself was patently mistaken, in a way that the reader of the press release probably should have caught with a bit of quick multiplication — a "rate of about one every 5 minutes" would be about 300 daily ((60/5) x 24), not about 2000 daily.

I posted my observation about both errors (in a little more detail than this recap) on the blog. I had also e-mailed this observation, again about both errors, to the Barometer and to the Women's Center.

The Barometer then published this correction:

Approximately, 2,000 rapes occur each day, or one about every five minutes. The Daily Barometer misprinted this fact in an article that appeared in the Jan. 19, 2006 edition of The Daily Barometer.

The Daily Barometer staff regrets any misunderstanding or inconveniences caused by this error.

Unfortunately, this corrects the first error, but not the second error. It is not a "fact," and can never be a fact, that "2,000 each day" would equal "one about every five minutes." Whoops. (The Women's Center doesn't seem to have corrected this assertion on its own Myths & Facts page.)

I don't mean to blow this out of proportion (speaking of multiplication). I suspect this newspaper is no better or worse than most student newspapers, or than many nonstudent newspapers. But I thought this was worth noting because I think it's emblematic of some of the weaknesses that newspapers often suffer from, especially a tendency to quote seemingly authoritative sources without skeptically examining them, and a lack of comfort with numbers that keeps many journalists from quickly spotting these sorts of errors.

I should also stress that I myself often make errors (though I hope not ones quite like this). But when I do, and when I don't correct them (or correct them incorrectly), others are quite right to point this out. The result of such corrections, I would hope, is more accuracy in the present, and more care in the future.

Comments
More Multiplication:

A comment to the follow-up to my "A Little Multiplication Could Have Gone a Long Way" post says:

What? You mean not everyone memorizes useless conversions like that there are 1440 minutes (or 86400 seconds) per day? What is this country coming to?

I'd have let this slip, but given that the whole thread was about multiplication -- and that I'm a math geek -- I just couldn't resist. First, knowing how many minutes there are in a day, it turns out, is not useless: Among other things, it would help journalists and press release authors avoid errors like the one I was blogging about.

But second, here's a secret -- you don't have to memorize the conversions. Even if you don't remember the conversion, you can still figure out how many minutes there are in a day, whenever you need to (for instance, if you want to check whether the item you're about to publish is accurate). How, you might ask? What occult science will give me this magical power? Why . . . multiplication!

In fact, you don't even know how to do multiplication, since there are, I'm told, electronic devices that can do it for you. All you need to know is that such an operation exists, and that it can be deployed to solve immensely difficult problems like the "how many 5-minute increments in a day" one? (To be fair, it also helps knowing about multiplication's partner in crime, division.)

As it happens, I do remember a rough estimate of the number of seconds in a year, partly because one runs into these "every X seconds/minutes Y happens" -- 30 million, or (for a better approximation) 10 million pi for math geeks. I don't remember the number of minutes or seconds in a day. But I am so learned that the numbers are nonetheless available to me whenever I please. And you too can have this fearsome power . . . .

Comments
Multiplication:

I've much enjoyed the discussion about the multiplication posts, and I agree that calculating in one's head is a good skill to have. Even if there's a calculator handy, people are often reluctant to use it (perhaps overestimating the effort it would take, or not wanting to look ignorant or skeptical), and if one can do even approximate calculations in one's head, one can often spot errors that one would have otherwise missed. Also, my sense is that learning arithmetic is good mental training for other thought processes, but I may be mistaken on that.

Nonetheless, my point was different: The important thing is not knowing how to multiply, but what, when, and why to multiply. Once you understand what calculation to do to check something, you can do it easily enough on a calculator. But the calculator won't explain to you how to structure the calculation, or whether a calculation ought to be done.

That, incidentally, is one reason that I'm so frustrated when people say "I never minded math" (usually referring to arithmetic or at most algebra) "in school, but I just never liked the word problems." All of life is word problems! A problem in the real world never comes to you as "figure out 123 x 456 + 789." Understanding how to translate the real-world condition into numbers is the important skill, not the calculation. And while most school-level word problems are usually only a very first step in that direction, if people can't master that first step, their knowledge of raw arithmetic or algebra won't help them actually deal with the world.

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