Did they consider the fact that certain kids (those most likely to have sex) may be more likely to listen to such music?
This is a really good question (and of course replies below yours chide, essentially, "no, they never think of that kind of obvious thing"). But in sciences, it is proper method to understand correlation differently than causation; HOWEVER if one were to propose a causal relatrionship one of the criteria would be that the stimulus must come BEFORE the outcome behavior.
That's exactly what this study finds. If they were looking at the rates of teen sex among teens who do and who don't listen to certain music types, including sexual behaviors that pre-date them becoming listeners, then the scientists could only note correlation.
But support of a causal relationship (not "proof," but support) is found in the fact that the study notes that 1) these teens listened to the music before the onset of actual sexual contact in their lives, and 2) when actual sexual activity began, it was EARLIER among those teens. In fact, the authors aptly note that the study can't be fairly applied to Blacks, generally, precisely BECAUSE that group was likelier to have already initiated their sexual behaviors in life. Thus, when the facts are inconsistent with the theory the authors appropriately note it, which belies the cynical "Of course they never would have considered something so common-sense" criticisms. See, the authors DID consider it, and were careful not to apply their theory to groups when that was the case. As is proper method.
(itr's worth noting that the study has appeared in peer-reviewed journals, which are very attentive to proper method and to rejecting lazy conclusions or poor design, and "Pediatrics" is a VERY tough journal in particular--not a propaganda publication)
The article above presents a salacious and sensationalized retelling of the study in a more folkloric approach, such as the use of Ipods as a storytelling propr (found NOWHERE in the original report).
Here's an earlier version of a story on the same study (note the different tone and more cautious wording):
Sexy media a siren call to promiscuity
Apr 3, 11:04 AM (ET)
By Michael Conlon
CHICAGO (Reuters) - Sexually charged music, magazines, TV and movies push youngsters into intercourse at an earlier age, perhaps by acting as kind of virtual peer that tells them everyone else is doing it, a study said Monday.
"This is the first time we've shown that the more kids are exposed to sex in media the earlier they have sex," said Jane Brown of the University of North Carolina, chief author of the report.
Previous research had been limited to television, said the study which looked at 1,017 adolescents when they were aged 12 to 14 and again two years later. They were checked on their exposure during the two years to 264 items -- movies, TV shows, music and magazines -- which were analyzed for their sexual content.
In general it found that the highest exposure levels led to more sexual activity, with white teens in the group 2.2 times more likely to have had intercourse at ages 14 to 16 than similar youngsters who had the least exposure.
The effect was not as pronounced for blacks, the study said, perhaps because the black youngsters in the study were already more sexually experienced than the whites were when the research began and thus were less influenced by media exposure over the two-year period.
The teenage pregnancy rate in the United States is three to 10 times higher than that found in other industrialized nations, making that and exposure to sexually transmitted infections a major public health concern, the study said.
At the same time parents tend not to talk about sex with their children in a timely and comprehensive way, leaving a vacuum in which the media may become a powerful sex educator, providing "frequent and compelling portraits of sex as fun and risk free."
"Interestingly one of the strongest predictors of risk for early sexual intercourse for both black and white teens (in the study) was the perception that his or her peers were having sex," the report said.
Youngsters "may begin to believe the world view portrayed and may begin to adopt the media's social norms as their own. Some, especially those who have fewer alternative sources of sexual norms, such as parents or friends, may use the media as a kind of sexual superpeer that encourages them to be sexually active," the report added.
The study was published in the April issue of "Pediatrics," the journal of the American Academy of Pediatrics. A portion of the data was previously published in the Journal of Adolescent Health.
The study was done in several schools in North Carolina. The authors said that they did not measure the impact of exposure to sexual material on the Internet because when the research began in 2001 relatively few of the early adolescents in the sample had Internet access.
Additional research should include exposure to Web-based material, the study suggested.
"It took many studies over a number of years to establish that violence in the media increased children's violent behavior and to begin initiatives to reduce harmful effects," the study said.
"Given the consistent findings regarding media violence, it may be prudent not to wait decades to conclude that the media are also important sources of sexual norms for youth," it added.