But Should We Believe It?

Fascinating, surprising -- even shocking. But accurate? With any survey, there is a risk that respondents will exaggerate, omit facts or otherwise fail to tell the whole truth and nothing but the truth. Especially on sensitive subjects like sexual behavior. There is also the risk that the sample will not represent a fair cross section. Both of these problems have plagued earlier sex surveys, including the landmark reports issued by Alfred Kinsey in the 1940s and '50s. The team from the University of Chicago that produced the new study was determined to do better.

Kinsey thought he'd never get a random sample of people to talk about sex -- and in the inhibited atmosphere of his day he was probably right. He settled for what social scientists call a "sample of convenience," finding volunteers where he could. His numbers were huge -- some 11,000 people -- but selective and self-selected. In later years, mail-in surveys conducted by magazines like Playboy and Redbook and by Shere Hite were still less representative. Even Masters and Johnson called their own classic study "admittedly prejudiced."

The Chicago team avoided this trap. Working with the school's National Opinion Research Center (NORC), the team began by using computers to select addresses at random. Then they chose which member of the household to interview, again at random. Next they rigorously trained a cadre of 220 interviewers on the delicate art of conducting a frank discussion of sex. "Our feeling was that you could get people to talk about anything if you approach them right," says Edward Laumann, a sociologist at the University of Chicago.

The interviews were conducted in person, though there was also a confidential form that included questions about masturbation and income. Many subjects were reluctant to participate, but the pollsters kept trying -- making up to 15 visits in some cases to win them over. In the end an impressive 79% of the sample group of 4,369 took part. There were built-in safeguards: some questions were asked more than once in different ways, ensuring that only a motivated liar could easily convey misinformation. Of the major sex surveys to date, says sociologist Ira Reiss of the University of Minnesota, this was "probably the best thought out and has the broadest coverage."

Inevitably, there are criticisms. One is that the absence of women among the study's directors could have skewed the questions. Doubts have also been raised about whether personal interviews could elicit truly candid answers to intimate questions. In addition, the sample is too small to look in detail at some groups, like homosexuals. But their careful work, the team writes, "has convinced us that this sample is an excellent one from which we can make generalizations about sex in America." And, they emphasize, "we do so with confidence."