Allow me to borrow from Mark Twain: there are lies, damn lies and spin. Spin is more deceptive than statistics because it captures our imagination, and statistics are merely a tool, a part of the story. It’s particularly irksome when those spinning a story wear lab coats. It seems that whenever a scientist speaks, all surrender. Being called unscientific is worse than being unpatriotic. At least the unpatriotic are rebels. The unscientific are just stupid.

In the name of science, modern zealots have spent the last decade attacking abstinence-only education. The story of abstinence only education was spun as another example of President Bush’s "War on Science". Despite the modest funds spent on abstinence education compared to comprehensive sex education, the contraceptive lobby has been wailing over its existence for the last eight years. Under President Obama many expect a shift towards more contraceptive and condom promotion.

At the end of last year the medical journal Pediatrics added to the spin with a study about teenagers who take virginity pledges. Some, but not all, programs that emphasise abstinence also encourage vows to wait until marriage. So a study about virginity pledges is really about abstinence.

But the study also sheds light on medical bias against abstinence. Its cynical title, "Patient Teens? A Comparison of Sexual Behavior of Virginity Pledgers and Matched Nonpledgers," is more appropriate for Nation or Mother Jones than a serious medical journal.

Despite its scepticism at teenage self control, author Jill Rosenbaum does acknowledge that previous studies have shown that virginity pledgers do delay sexual activity. So the purpose of her longitudinal study was to determine whether a virginity pledge alone is sufficient to delay sexual activity.

Previous studies had shown that pledgers came from the same demographic and economic background as other teenagers. But little was known about their attitudes towards sex and religion. So Dr Rosenbaum analysed surveys of sexual behaviour of teenagers who were at least 15 and surveys taken five years later. Did the pledgers keep their word?

Surprise, surprise, the sexual behaviour of both pledgers and peers who had traditional attitudes towards sex and were very religious but had not taken a pledge was more or less the same. Rosenbaum triumphantly concluded that virginity pledges don’t change sexual behaviour. Then she polished off her demolition of abstinence with statistics showing that pledgers are also less likely to use contraceptives and condoms. The lesson is that abstinence-only education is not only hypocritical but also unscientific and stupid.

What did the media make of this?

This was how the Washington Post summarised the study: "Teenagers who pledge to remain virgins until marriage are just as likely to have premarital sex as those who do not promise abstinence." Web MD, a popular website for medical advice, announced that "Teenagers Who Take Virginity Pledges No Less Sexually Active". MedPage, another popular website, advised doctors to explain to patients that that funding for abstinence-only programs should be diverted to evidence-based sex education programs that teach birth control.

The mangled statistics in these reports makes me despair of the intelligence of journalists, not of teenagers. What if I were to study whether teenagers who read Dickens are more likely to enter college? If they are motivated enough to read Dickens, they are probably avid readers anyway. So it makes no sense to compare them with teenagers who read Austen, Thackeray, Bronte, Eliot, Hardy and Kipling, but not Dickens. To find out if reading Dickens makes a difference, you should compare them to all teens, whatever their reading habits.

So the newspapers omitted the real story. Sure, the sexual behaviour of pledgers was the same as their "peers", BUT it was "substantially more conservative… than the general population of adolescents," in Rosenbaum’s words. Religious teens, whether they had taken a virginity pledge or not, were less likely to report premarital sex or multiple sex partners. In fact, the average age of sexual initiation was 21 for the pledgers, four whole years longer than for the general population of adolescents. In other words, Dr Rosenbaum’s spin transformed a huge success into a tale of failure and futility.

Were there any reasons other than ineptitude why the reporting was so distorted?

Bias against chastity is a big one. Abstinence-only education is held to a different standard than comprehensive sexual education. When compared to contraceptive sex education, even its critics grudgingly admit that abstinence education does delay sexual activity significantly. But they have the gall to describe these programs as failures because teenagers fail to enter marriage as virgins. But would you call an AA veteran a failure if he had a beer after 20 years of sobriety?

Most condom hustlers and journalists believe that abstinence should be exhibited in a museum along with the rhythm method and chastity belts. Dr. Rosenbaum and Pediatrics now have a new exhibit, the virginity pledge.

Like a racehorse with blinders, running in an ideological circle, Rosenbaum and the media ignore the fact that the initiation of sexual activity until after high school spells the difference between success and failure for many teens. The Heritage Foundation has found that teenagers who abstain from sexual activity during high school are less likely to drop out of school and twice as likely to graduate from college. Studies also show that 25 percent of sexually active teenage girls report feeling depressed compared to 7.7 percent of girls who are not sexually active. As they say, virtue is its own reward. Abstinence offers benefits which neither condoms nor contraceptives can provide.

The real story of "Patient Teens?" is not about wayward teenagers. It’s about the alarming emergence appearance of a new medical specialist, the spin doctor.