Lou Dobbs’ Bad Math on Leprosy

Carl Zimmer’s The Loom occupies a prominent place in my RSS reader, and right now, he and his readers are chatting it up about how Web 2.0 (or perhaps Web 3.1, Web 95 or Web ME) can help the cause of science journalism. Go and contribute! (My own thoughts run along a slightly different track: what are the shortcomings of Web 2.0 which we can address while improving the communication of science?)

And now that we’re thinking about journalism, I’d like to call the Gentle Readers’ attention to Dean Starkman’s piece in the Columbia Journalism Review blag discussing Lou Dobbs and leprosy. The short version is this: Dobbs said that 7,000 new cases of leprosy have occurred in the United States during the past three years. That’s not true. The real number is 431. Dobbs went uncorrected by NPR and 60 Minutes, and was not called out until today’s New York Times. As David Leonhardt writes in that publication,

When Lesley Stahl of “60 Minutes” sat down to interview Mr. Dobbs on camera, she mentioned the report and told him that there didn’t seem to be much evidence for it.

“Well, I can tell you this,” he replied. “If we reported it, it’s a fact.”

Unfortunately for Dobbs, numbers are not so pliable. (For example, reporting that the number of Iraqi WMDs was greater than zero did not make that assessment a fact.) To understand this situation, we should backtrack to the source.

Back in 2005, Dobbs’ show ran a segment which claimed, “the invasion of illegal immigrants is threatening the health of many Americans.” They quoted Dr. Madeline Cosman (1937–2006), whom they billed as a “medical lawyer.” Chatting after the segment, the reporter (Christine Romans) ad-libbed:

It’s interesting because the woman in our piece [Cosman] told us that there were 900 cases for 40 years. There have been 7,000 in the past three years. Leprosy in this country.

Leprosy is, of course, an evocative disease. It provokes memories of Sunday school, of stories about Jesus casting out the evil spirits. I’ll wager that since it is also a comparatively rare disease, New Testament allusions are the most prominent associations for many people. Not surprisingly, Cosman invokes this very trope:

Leprosy, a scourge of Biblical days and Medieval Europe so horribly destroys flesh and faces it was called the disease of the soul. (70) Lepers quarantined in leprosaria sounded noisemakers when they ventured out to warn people to stay far away. Leprosy, Hansen’s disease, was so rare in America that in 40 years only 900 people were afflicted. (71, 72) Suddenly, in the past three years, America has more than 7,000 cases. Leprosy is now endemic to northeastern states because illegal aliens and immigrants brought leprosy from India, Brazil, the Caribbean and Mexico.(53, 73, 74)

Nope. The Department of Health and Human Services keeps track of these things; that’s their job. Government records show roughly 6,500 total cases in the United States, of which about 3,300 require active medical treatment. Those 6,500 cases were accumulated over thirty years! The DHHS notes that standard antibiotics are still very effective against leprosy (also referred to as Hansen’s disease), most of the human population is not susceptible to M. leprae infection, and in fact, “the psychological and social effects may be more difficult to deal with than the actual physical illness.”

Starkman summarizes:

The peak was 1985, at 450 new cases. In 2005, there were 166 new cases, thirty-one more than the year before. In the three most recent years of data, 2003-2005, there were 431 new cases.

(Also, by the way, leprosy is not “now endemic” to the northeast, either, as Cosman says, so we Brooklynites can relax.)

This case also illustrates one of the classic tricks explained in Darrell Huff’s classic How to Lie With Statistics (1954, reissued 1993): shifting baselines to juggle percentages.

Okay, one could say, accurately, that leprosy has more than doubled in the U.S. since 2000 (from seventy-six new cases to 166). Then again, one could say it has fallen 63 percent since 1985. Or one could say nothing at all, which is really what you should say. No leprosy story here.

Neither 60 Minutes nor NPR gave Dobbs the smackdown he deserved for citing bad numbers. (NPR tried gamely, but failed.) He says one thing, the facts say another — what’s so complicated about that?

Leonhardt says in the Times, “Mr. Dobbs has a somewhat flexible relationship with reality.” For example, he’s claimed that one third of federal prison inmates are illegal immigrants, when the actual figure for state and federal correctional facilities combined is only 6.4 percent. (If you look at federal facilities alone — and I’m not sure why you’d want to — you can bump up the figure to 19%, but 19% is not 33%.) Leonhardt continues,

Second, Mr. Dobbs really does give airtime to white supremacy sympathizers. Ms. Cosman, who is now deceased, was a lawyer and Renaissance studies scholar, never a medical doctor or a leprosy expert. She gave speeches in which she said that Mexican immigrants had a habit of molesting children. Back in their home villages, she would explain, rape was not as serious a crime as cow stealing. The Southern Poverty Law Center keeps a list of other such guests from “Lou Dobbs Tonight.”

Leonhardt’s conclusion is worth repeating:

Americans, as a rule, are smart enough to handle a program that mixes opinion and facts. The problem with Mr. Dobbs is that he mixes opinion and untruths. He is the heir to the nativist tradition that has long used fiction and conspiracy theories as a weapon against the Irish, the Italians, the Chinese, the Jews and, now, the Mexicans. […] More to the point, if Mr. Dobbs’s arguments were really so good, don’t you think he would be able to stick to the facts? And if CNN were serious about being “the most trusted name in news,” as it claims to be, don’t you think it would be big enough to issue an actual correction?

One of the nice things about using numbers is that people who employ them can be proven conclusively wrong. That is a power worthy of respect.